drm/i915: Move WaPruneModeWithIncorrectHsyncOffset into intel_mode_valid()

Check for the zero length front porch already in intel_mode_valid()
so that we get the same validation for both get_modes() and setcrtc()/etc.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210930104133.30854-3-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_display.c

@@ -4046,13 +4046,6 @@ static int intel_crtc_compute_config(struct intel_crtc *crtc,
 		}
 	}
 
-	/* Cantiga+ cannot handle modes with a hsync front porch of 0.
-	 * WaPruneModeWithIncorrectHsyncOffset:ctg,elk,ilk,snb,ivb,vlv,hsw.
-	 */
-	if ((DISPLAY_VER(dev_priv) > 4 || IS_G4X(dev_priv)) &&
-	    pipe_mode->crtc_hsync_start == pipe_mode->crtc_hdisplay)
-		return -EINVAL;
-
 	intel_crtc_compute_pixel_rate(pipe_config);
 
 	if (pipe_config->has_pch_encoder)
@@ -11159,6 +11152,14 @@ intel_mode_valid(struct drm_device *dev,
 			return MODE_V_ILLEGAL;
 	}
 
+	/*
+	 * Cantiga+ cannot handle modes with a hsync front porch of 0.
+	 * WaPruneModeWithIncorrectHsyncOffset:ctg,elk,ilk,snb,ivb,vlv,hsw.
+	 */
+	if ((DISPLAY_VER(dev_priv) > 4 || IS_G4X(dev_priv)) &&
+	    mode->hsync_start == mode->hdisplay)
+		return MODE_H_ILLEGAL;
+
 	return MODE_OK;
 }