staging: rtl8723bs: os_dep: Change return type of rtw_init_default_value() to void

rtw_init_default_value() func always returns a value (u8)_SUCCESS.
Modified return type to void to resolve coccicheck warnings
of unneeded variable.

Signed-off-by: Shobhit Kukreti <shobhitkukreti@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>