drm/i915: Force planar YUV coordinates to be a multiple of 2, v2.

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