staging: r8188eu: make validate_recv_ctrl_frame return void

Make validate_recv_ctrl_frame return void.

At the moment, the function always returns _FAIL, the caller does not
check the return value.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220403164526.357371-2-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>