staging: rtl8723bs: Macros with complex values should be enclosed in parentheses

Enclosing macros with complex values ensures expression is evaluated as
expected.

Signed-off-by: Justin Vreeland <justin@jvreeland.com>
Reviewed-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>