staging: rtl8192u: Add space after enum definition

Fix checkpatch.pl warning:
WARNING:missing space after enum definition

Signed-off-by: Melike Yurtoglu <aysemelikeyurtoglu@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>