drm: set permissions on edid file to 0444

Without initializing the sysfs attributes for the edid file,
it was created with mode 0, making it difficult for applications to use.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_sysfs.c

@@ -317,6 +317,7 @@ static struct device_attribute connector_attrs_opt1[] = {
 
 static struct bin_attribute edid_attr = {
 	.attr.name = "edid",
+	.attr.mode = 0444,
 	.size = 128,
 	.read = edid_show,
 };