drm: Constify TV mode names

Make the mode names passed to drm_mode_create_tv_properties() const.

 drivers/gpu/drm/i2c/ch7006.ko:
-.rodata                       596
+.rodata                       664
-.data                        7064
+.data                        6992

 drivers/gpu/drm/nouveau/nouveau.ko:
-.rodata                      146808
+.rodata                      146904
-.data                        178624
+.data                        178528

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 884690c..474f328 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1519,7 +1519,7 @@
  */
 int drm_mode_create_tv_properties(struct drm_device *dev,
 				  unsigned int num_modes,
-				  char *modes[])
+				  const char * const modes[])
 {
 	struct drm_property *tv_selector;
 	struct drm_property *tv_subconnector;