staging: rtl8723bs: add space after enum declaration

Add space between "enum TXDESC_SC" and '{' at line 86.

Fix the following error from checkpatch.pl

WARNING: missing space after enum definition
+enum TXDESC_SC{

Signed-off-by: William Tustumi <whatust@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>