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_drv.c b/drivers/gpu/drm/i2c/ch7006_drv.c
index 51fa323..d9a72c9 100644
--- a/drivers/gpu/drm/i2c/ch7006_drv.c
+++ b/drivers/gpu/drm/i2c/ch7006_drv.c
@@ -119,8 +119,8 @@
 	struct ch7006_encoder_params *params = &priv->params;
 	struct ch7006_state *state = &priv->state;
 	uint8_t *regs = state->regs;
-	struct ch7006_mode *mode = priv->mode;
-	struct ch7006_tv_norm_info *norm = &ch7006_tv_norms[priv->norm];
+	const struct ch7006_mode *mode = priv->mode;
+	const struct ch7006_tv_norm_info *norm = &ch7006_tv_norms[priv->norm];
 	int start_active;
 
 	ch7006_dbg(client, "\n");
@@ -226,7 +226,7 @@
 				    struct drm_connector *connector)
 {
 	struct ch7006_priv *priv = to_ch7006_priv(encoder);
-	struct ch7006_mode *mode;
+	const struct ch7006_mode *mode;
 	int n = 0;
 
 	for (mode = ch7006_modes; mode->mode.clock; mode++) {