drm: Constify drm_mode_config_funcs pointer

The DRM mode config functions structure declared by drivers and pointed
to by the drm_mode_config funcs field is never modified. Make it a const
pointer.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Rob Clark <rob.clark@linaro.org>
Reviwed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index da3fe8a..64a008d1 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -1320,7 +1320,7 @@
 	drm_mode_config_init(rdev->ddev);
 	rdev->mode_info.mode_config_initialized = true;
 
-	rdev->ddev->mode_config.funcs = (void *)&radeon_mode_funcs;
+	rdev->ddev->mode_config.funcs = &radeon_mode_funcs;
 
 	if (ASIC_IS_DCE5(rdev)) {
 		rdev->ddev->mode_config.max_width = 16384;