drm/i915/display: Save a few bytes of memory in intel_backlight_device_register()

'name' may still be "intel_backlight" when backlight_device_register()
is called. In such a case, using kstrdup_const() saves a memory
duplication when dev_set_name() is called in
backlight_device_register().

Use kfree_const() accordingly.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ecfdb3af5005e05131e2fb93fd870830f39a8c29.1708708142.git.christophe.jaillet@wanadoo.frSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_backlight.c

@@ -949,7 +949,7 @@ int intel_backlight_device_register(struct intel_connector *connector)
 	else
 		props.power = FB_BLANK_POWERDOWN;
 
-	name = kstrdup("intel_backlight", GFP_KERNEL);
+	name = kstrdup_const("intel_backlight", GFP_KERNEL);
 	if (!name)
 		return -ENOMEM;
 
@@ -963,7 +963,7 @@ int intel_backlight_device_register(struct intel_connector *connector)
 		 * compatibility. Use unique names for subsequent backlight devices as a
 		 * fallback when the default name already exists.
 		 */
-		kfree(name);
+		kfree_const(name);
 		name = kasprintf(GFP_KERNEL, "card%d-%s-backlight",
 				 i915->drm.primary->index, connector->base.name);
 		if (!name)
@@ -987,7 +987,7 @@ int intel_backlight_device_register(struct intel_connector *connector)
 		    connector->base.base.id, connector->base.name, name);
 
 out:
-	kfree(name);
+	kfree_const(name);
 
 	return ret;
 }