wifi: rtl8xxxu: mark Edimax EW-7811Un V2 as tested

The Edimax V2 (vid 0x7392, pid 0xb811) works well with the rtl8xxxu driver
since rtl8188eu support has been added. Remove the untested flag for this
device.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230305175932.719103-1-martin@kaiser.cx