drm: Introduce a crtc_clock for struct drm_display_mode

Just like the various timings, make it possible to have a clock field
what we can tweak before giving it to hardware.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_modes.c

@@ -719,6 +719,7 @@ void drm_mode_set_crtcinfo(struct drm_display_mode *p, int adjust_flags)
 	if ((p == NULL) || ((p->type & DRM_MODE_TYPE_CRTC_C) == DRM_MODE_TYPE_BUILTIN))
 		return;
 
+	p->crtc_clock = p->clock;
 	p->crtc_hdisplay = p->hdisplay;
 	p->crtc_hsync_start = p->hsync_start;
 	p->crtc_hsync_end = p->hsync_end;

include/drm/drm_crtc.h

@@ -156,6 +156,7 @@ struct drm_display_mode {
 	int height_mm;
 
 	/* Actual mode we give to hw */
+	int crtc_clock;		/* in KHz */
 	int crtc_hdisplay;
 	int crtc_hblank_start;
 	int crtc_hblank_end;