staging: rtl8723bs: Change return type of networktype_to_raid_ex()

Change return type of header file prototype of networktype_to_raid_ex
from unsigned char to u8 to match its actual definition and call site.

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