ENGR00254931 IPUv3 Fb: Fix display twinkling issue during suspend/resume

ENGR00254931 IPUv3 Fb: Fix display twinkling issue during suspend/resume

Fix display twinkling issue when video playback on LVDS during suspend/resume.
The issue happens when the rootfs application Xfbdev calls fb_set_var() for IPU
BG fb to unblank the console, so it wants to reinitialize the IPU BG. However,
IPU FG is still being used for video playback.It is reasonable to refuse
reprogramme because of the resources confilct.

Signed-off-by: Wayne Zou <b36644@freescale.com>