linux-imx

drm/imx: dpu: kms: Return properly in case we fail to get plane state to check

We should return properly in case we fail to get plane state to check.
For example, a race condition on the plane state would happen when one
thread does page flip and another thread updates CRTC properties on
that CRTC simultaneously.  '-EDEADLK' should be returned when the
condition occurs.

Signed-off-by: Liu Ying <victor.liu@nxp.com>