video: fbdev: offb: fix warning comparing pointer to 0

Fix the following coccicheck warning:
drivers/video/fbdev/offb.c:415:13-14: WARNING comparing pointer to 0

Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Signed-off-by: Helge Deller <deller@gmx.de>
1 file changed