Staging: xgifb: braces {} are not necessary for single statement in vb_setmode

Fix checkpatch.pl issues with braces {} are not necessary
for single statement blocks in vb_setmode.c

Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>