drm: avoid warning in drm_load_edid_firmware()

Use "const char *" instead of "char *" in order to avoid this warning:

  drivers/gpu/drm/drm_edid_load.c: In function ‘drm_load_edid_firmware’:
  drivers/gpu/drm/drm_edid_load.c:245:25: warning: initialization discards ‘const’ qualifier from pointer target type [enabled by default]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/drm_edid_load.c

@@ -133,8 +133,8 @@ static u8 generic_edid[GENERIC_EDIDS][128] = {
 	},
 };
 
-static u8 *edid_load(struct drm_connector *connector, char *name,
-			char *connector_name)
+static u8 *edid_load(struct drm_connector *connector, const char *name,
+			const char *connector_name)
 {
 	const struct firmware *fw;
 	struct platform_device *pdev;
@@ -242,7 +242,7 @@ static u8 *edid_load(struct drm_connector *connector, char *name,
 
 int drm_load_edid_firmware(struct drm_connector *connector)
 {
-	char *connector_name = drm_get_connector_name(connector);
+	const char *connector_name = drm_get_connector_name(connector);
 	char *edidname = edid_firmware, *last, *colon;
 	int ret;
 	struct edid *edid;