drm: Pass the display mode to drm_calc_timestamping_constants()

We don't really use hwmode anymore in i915, so eliminating its use
from the core code seems prudent. Just pass the appropriate mode
to drm_calc_timestamping_constants().

Reviewed-by: mario.kleiner.de@gmail.com
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 01361ab..245fe4f 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -536,7 +536,7 @@
 	 * are later needed by vblank and swap-completion
 	 * timestamping. They are derived from true hwmode.
 	 */
-	drm_calc_timestamping_constants(crtc);
+	drm_calc_timestamping_constants(crtc, &crtc->hwmode);
 
 	/* FIXME: add subpixel order */
 done: