staging: xgifb: vb_setmode: fix multiple line dereference

Fix multiple line dereference by adding a new line and adjusting
indentations. This change improves code readability. Issue found by
checkpatch.

Signed-off-by: Kimberly Brown <kimbrownkd@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>