udev: Don't only check 'platform' device for KMS modifier tag

Only checking the 'platform' device missed the tags added for i915 and
others, meaning the multi head configurations yet again started to fail
due to default modifier behavior is incompatible with multi many head
configurations.

Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1769
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1774
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1843>

src/backends/native/meta-udev.c

@@ -77,22 +77,21 @@ meta_is_udev_device_boot_vga (GUdevDevice *device)
 gboolean
 meta_is_udev_device_disable_modifiers (GUdevDevice *device)
 {
-  g_autoptr (GUdevDevice) platform_device = NULL;
   const char * const * tags;
+  g_autoptr (GUdevDevice) platform_device = NULL;
+
+  tags = g_udev_device_get_tags (device);
+  if (tags && g_strv_contains (tags, "mutter-device-disable-kms-modifiers"))
+    return TRUE;
 
   platform_device = g_udev_device_get_parent_with_subsystem (device,
                                                              "platform",
                                                              NULL);
 
-  if (!platform_device)
+  if (platform_device)
+    return meta_is_udev_device_disable_modifiers (platform_device);
+  else
     return FALSE;
-
-  tags = g_udev_device_get_tags (platform_device);
-
-  if (!tags)
-    return FALSE;
-
-  return g_strv_contains (tags, "mutter-device-disable-kms-modifiers");
 }
 
 gboolean