MA-19724 drm/imx: lcdif: Defer suspend sequence

evk_8mn will meet system hang when resume (using
"echo mem > /sys/power/state" to make system suspend
while display on).
The reason is that imx-drm driver resumes before
imx-lcdif driver, and access some hardware while
those resources not ready.

fw_devlink will affect the suspend/resume sequence
by parsing dts to create dependency btw drivers.
But these two drivers doesn't have supported dts
property for fw_devlink.

This patch explicitly defers the suspend sequence
of imx-lcdif driver to fix it.

Change-Id: Ifd266101650c07fecdbfcbdcb9231f9aa4b4f70a
Signed-off-by: Jindong Yue <jindong.yue@nxp.com>