video: fbdev: pxafb: potential NULL dereference on error

If we "goto out;" then it calls display_timings_release(timings);
Since "timings" is NULL, that's going to oops.  Just return directly.

Fixes: 420a4882 ('video: fbdev: pxafb: initial devicetree conversion')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>