Staging: rtl8192u: Remove space before ','

This patch fixes checkpatch.pl error in file r8190_rtl8256.h
ERROR: space prohibited before that ',' (ctx:WxW)

Signed-off-by: Dilek Uzulmez <dilekuzulmez@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>