r8712u: Update to latest firmware

A new firmware file is used in the vendor driver with name/version
rtl8188C_8192C_8192D_usb_linux_v3.4.2_3727.20120404.
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

WHENCE

@@ -1747,7 +1747,7 @@ Licence:
 Driver: r8712u - Realtek 802.11n WLAN driver for RTL8712U
 
 File: rtlwifi/rtl8712u.bin
-Info: version found in the Vendor's V2.6.6
+Info: From Vendor's rtl8188C_8192C_8192D_usb_linux_v3.4.2_3727.20120404
 
 Licence: Redistributable. See LICENCE.rtlwifi_firmware.txt for details.