staging: rtl8712: aes_decipher(): Change return type

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

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190802064212.30476-8-nishkadg.linux@gmail.com


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