imx-drm plane, build warning, and error handling fixes
- some fixes for active plane reconfiguration support
- hide unused label in case of disabled CONFIG_DRM_FBDEV_EMULATION,
which caused a build warning
- fixed error handling in imx_drm_bind
- disallow odd x/y plane offsets for chroma subsampled formats
- disable local alpha when switching from a format with alpha
channel to an opaque format
* tag 'imx-drm-fixes-
20161021' of git://git.pengutronix.de/pza/linux:
drm/imx: ipuv3-plane: disable local alpha for planes without alpha channel
drm/imx: ipuv3-plane: make sure x/y offsets are even in case of chroma subsampling
drm/imx: ipuv3-plane: Access old u/vbo properly in ->atomic_check for YU12/YV12
drm/imx: drm_dev_alloc() returns error pointers
drm/imx: ipuv3-plane: Skip setting u/vbo only when we don't need modeset
drm/imx: ipuv3-plane: Switch EBA buffer only when we don't need modeset
gpu: ipu-v3: Use ERR_CAST instead of ERR_PTR(PTR_ERR())
drm/imx: hide an unused label