MLK-11700 video: mxsfb: correct the fb pan display ret value

The fb_pan_display() return value should be corrected
according to the wait_for_completion_timeout() return
value.

Signed-off-by: Fancy Fang <chen.fang@freescale.com>
(cherry picked from commit 459d01cb)

Conflicts:
	drivers/video/mxsfb.c