verifiers: ARM Xen fallout cleanup

ARM Xen fallout cleanup after commit ca0a4f689 (verifiers: File type for
fine-grained signature-verification controlling).

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>

include/grub/file.h

@@ -42,6 +42,11 @@ enum grub_file_type
     /* Multiboot module.  */
     GRUB_FILE_TYPE_MULTIBOOT_MODULE,
 
+    /* Xen hypervisor - used on ARM only. */
+    GRUB_FILE_TYPE_XEN_HYPERVISOR,
+    /* Xen module - used on ARM only. */
+    GRUB_FILE_TYPE_XEN_MODULE,
+
     GRUB_FILE_TYPE_BSD_KERNEL,
     GRUB_FILE_TYPE_FREEBSD_ENV,
     GRUB_FILE_TYPE_FREEBSD_MODULE,