drm/i915: release cursor when crtc is destroyed

crtc is holding a reference to a cursor bo and it needs
to be released when crtc is destroyed so that we don't leak
the cursor bo.

v2: Enhance set and move cursor so that disabled
cursor is handled correctly (Ville Syrjälä)
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -6509,7 +6509,7 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 	intel_crtc->cursor_width = width;
 	intel_crtc->cursor_height = height;
 
-	intel_crtc_update_cursor(crtc, true);
+	intel_crtc_update_cursor(crtc, intel_crtc->cursor_bo != NULL);
 
 	return 0;
 fail_unpin:
@@ -6528,7 +6528,7 @@ static int intel_crtc_cursor_move(struct drm_crtc *crtc, int x, int y)
 	intel_crtc->cursor_x = x;
 	intel_crtc->cursor_y = y;
 
-	intel_crtc_update_cursor(crtc, true);
+	intel_crtc_update_cursor(crtc, intel_crtc->cursor_bo != NULL);
 
 	return 0;
 }
@@ -7042,6 +7042,8 @@ static void intel_crtc_destroy(struct drm_crtc *crtc)
 		kfree(work);
 	}
 
+	intel_crtc_cursor_set(crtc, NULL, 0, 0, 0);
+
 	drm_crtc_cleanup(crtc);
 
 	kfree(intel_crtc);