drm/i915: Use the per-plane rotation property

On certain platforms not all planes support the same set of
rotations/reflections, so let's use the per-plane property
for this.

This is already a problem on SKL when we use the legay cursor plane
as it only supports 0|180 whereas the universal planes support
0|90|180|270, and it will be a problem on CHV soon.

v2: Use drm_plane_create_rotation_property() helper
v3: Drop the BIT(), use INTEL_GEN()

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v1)
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1474907460-10717-12-git-send-email-ville.syrjala@linux.intel.com