drm: Make the .mode_fixup() operations mode argument a const pointer

The passed mode must not be modified by the operation, make it const.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/gma500/mdfld_intel_display.c b/drivers/gpu/drm/gma500/mdfld_intel_display.c
index 3f3cd61..dec6a9a 100644
--- a/drivers/gpu/drm/gma500/mdfld_intel_display.c
+++ b/drivers/gpu/drm/gma500/mdfld_intel_display.c
@@ -117,7 +117,7 @@
 }
 
 static bool psb_intel_crtc_mode_fixup(struct drm_crtc *crtc,
-				  struct drm_display_mode *mode,
+				  const struct drm_display_mode *mode,
 				  struct drm_display_mode *adjusted_mode)
 {
 	return true;