staging: rtl8723bs: os_dep: ioctl_linux.c: Remove return variables

Remove return variables and in multiple functions and return the values
directly, as the functions all return 0 in all cases.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>