staging: rtl8712: r8712_tkip_decrypt(): Change return type

Change return type of r8712_tkip_decrypt from u8 to void as the
return value is never used. Modify or remove return statements
accordingly.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190802064212.30476-6-nishkadg.linux@gmail.com


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