drm/i915: use the mode->htotal to calculate linetime watermarks

... instead of mode->crtc_display. The spec says "pipe horizontal
total number of pixels" and the "Haswell Watermark Calculator" tool
uses the "Pipe H Total" instead of "Pipe H Src" as the value.
Signed-off-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -2093,7 +2093,7 @@ haswell_update_linetime_wm(struct drm_device *dev, struct drm_crtc *crtc)
 	 * row at the given clock rate, multiplied by 8.
 	 * */
 	temp |= PIPE_WM_LINETIME_TIME(
-		((mode->crtc_hdisplay * 1000) / mode->clock) * 8);
+		((mode->htotal * 1000) / mode->clock) * 8);
 
 	/* IPS watermarks are only used by pipe A, and are ignored by
 	 * pipes B and C.  They are calculated similarly to the common