drm/i915: Make disable_cursor_plane similar to commit_cursor_plane.

Update cursor_addr when disable_plane is called.
This is required to make commit_cursor_plane take a
crtc_state and a plane_state.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452164052-21752-5-git-send-email-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4fe0c4d..0483c24 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14256,6 +14256,9 @@
 intel_disable_cursor_plane(struct drm_plane *plane,
 			   struct drm_crtc *crtc)
 {
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+
+	intel_crtc->cursor_addr = 0;
 	intel_crtc_update_cursor(crtc, false);
 }