staging: rtl8712: aes_cipher(): Change return type

Change return type of aes_cipher from sint to void as it always returns
_SUCCESS and its return value is never used.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190802064212.30476-7-nishkadg.linux@gmail.com


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