We can't make NV12 work any other way. The scaler doesn't handle odd
coordinates well, and we will get visual corruption on the screen.

Changes since v1:
- Put the check in intel_plane_check_src_coordinates. (Ville)
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180920102711.4184-9-maarten.lankhorst@linux.intel.com