drm/i915: Enable querying offset of UV plane with intel_plane_obj_offset

v2: Rebase.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index ad0e7e0..bbb96a4 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -3332,6 +3332,8 @@
 		if (offset_in_page(rot_info->uv_offset))
 			uv_start_page--;
 
+		rot_info->uv_start_page = uv_start_page;
+
 		rotate_pages(page_addr_list, uv_start_page,
 			     rot_info->width_pages_uv,
 			     rot_info->height_pages_uv,