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/include/drm/drmP.h b/include/drm/drmP.h
index 63eab2b7..46bf8ae 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1402,7 +1402,8 @@
 						 struct timeval *vblank_time,
 						 unsigned flags,
 						 struct drm_crtc *refcrtc);
-extern void drm_calc_timestamping_constants(struct drm_crtc *crtc);
+extern void drm_calc_timestamping_constants(struct drm_crtc *crtc,
+					    const struct drm_display_mode *mode);
 
 extern bool
 drm_mode_parse_command_line_for_connector(const char *mode_option,