staging: rtl8712: r8712_free_recvframe(): Change return type

Change return type of r8712_free_recvframe from int 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/20190722092341.21030-8-nishkadg.linux@gmail.com


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