The Realtek RTL8188SU chipset requires the non-free firmware rtl8192sfw.bin to get it work.

lsusb -v

Bus 001 Device 006: ID 0bda:8171 Realtek Semiconductor Corp. RTL8188SU 802.11n WLAN Adapter
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        64
  idVendor           0x0bda Realtek Semiconductor Corp.
  idProduct          0x8171 RTL8188SU 802.11n WLAN Adapter
  bcdDevice            2.00
  iManufacturer           1 Manufacturer Realtek
  iProduct                2 11n USB Adapter
  iSerial                 3 00e04c000001
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           46
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           4
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass    255 Vendor Specific Subclass
      bInterfaceProtocol    255 Vendor Specific Protocol
      iInterface              0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x04  EP 4 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x06  EP 6 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x0d  EP 13 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
Device Qualifier (for other device speed):
  bLength                10
  bDescriptorType         6
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        64
  bNumConfigurations      1
Device Status:     0x0000
  (Bus Powered)

dmesg

[ 3345.396414] usb 3-2: new high-speed USB device number 2 using ehci-pci
[ 3345.782885] r8712u: module is from the staging directory, the quality is unknown, you have been warned.
[ 3345.787954] r8712u: Staging version
[ 3345.788042] r8712u: register rtl8712_netdev_ops to netdev_ops
[ 3345.788058] usb 3-2: r8712u: USB_SPEED_HIGH with 4 endpoints
[ 3345.791829] usb 3-2: r8712u: Boot from EFUSE: Autoload OK
[ 3346.559825] usb 3-2: r8712u: CustomerID = 0x0000
[ 3346.559842] usb 3-2: r8712u: MAC Address from efuse = b0:48:7a:90:9b:4d
[ 3346.559850] usb 3-2: r8712u: Loading firmware from "/*(DEBLOBBED)*/"
[ 3346.559856] 3-2: Missing Free firmware
[ 3346.559871] usb 3-2: r8712u: Firmware request error -22