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/i2c/ch7006_mode.c b/drivers/gpu/drm/i2c/ch7006_mode.c
index 9b83574..f4dca53 100644
--- a/drivers/gpu/drm/i2c/ch7006_mode.c
+++ b/drivers/gpu/drm/i2c/ch7006_mode.c
@@ -26,7 +26,7 @@
 
 #include "ch7006_priv.h"
 
-char *ch7006_tv_norm_names[] = {
+const char * const ch7006_tv_norm_names[] = {
 	[TV_NORM_PAL] = "PAL",
 	[TV_NORM_PAL_M] = "PAL-M",
 	[TV_NORM_PAL_N] = "PAL-N",
@@ -202,7 +202,7 @@
 	struct i2c_client *client = drm_i2c_encoder_get_client(encoder);
 	struct ch7006_priv *priv = to_ch7006_priv(encoder);
 	uint8_t *regs = priv->state.regs;
-	struct ch7006_tv_norm_info *norm = &ch7006_tv_norms[priv->norm];
+	const struct ch7006_tv_norm_info *norm = &ch7006_tv_norms[priv->norm];
 	int gain;
 	int black_level;