Enforce disabling of firmware disk drivers when native drivers kick in.

grub-core/disk/efi/efidisk.c

@@ -623,22 +623,27 @@ static struct grub_disk_dev grub_efidisk_dev =
     .next = 0
   };
 
-void
-grub_efidisk_init (void)
-{
-  enumerate_disks ();
-  grub_disk_dev_register (&grub_efidisk_dev);
-}
-
 void
 grub_efidisk_fini (void)
 {
   free_devices (fd_devices);
   free_devices (hd_devices);
   free_devices (cd_devices);
+  fd_devices = 0;
+  hd_devices = 0;
+  cd_devices = 0;
   grub_disk_dev_unregister (&grub_efidisk_dev);
 }
 
+void
+grub_efidisk_init (void)
+{
+  grub_disk_firmware_fini = grub_efidisk_fini;
+
+  enumerate_disks ();
+  grub_disk_dev_register (&grub_efidisk_dev);
+}
+
 /* Some utility functions to map GRUB devices with EFI devices.  */
 grub_efi_handle_t
 grub_efidisk_get_device_handle (grub_disk_t disk)