arm64: Move firmware fdt search into global function

Searching for a device tree that EFI passes to us via configuration tables
is nothing architecture specific. Move it into generic code.

Signed-off-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/kern/efi/init.c

@@ -72,6 +72,28 @@ grub_machine_get_bootlocation (char **device, char **path)
     }
 }
 
+void *
+grub_efi_get_firmware_fdt (void)
+{
+  grub_efi_configuration_table_t *tables;
+  grub_efi_guid_t fdt_guid = GRUB_EFI_DEVICE_TREE_GUID;
+  void *firmware_fdt = NULL;
+  unsigned int i;
+
+  /* Look for FDT in UEFI config tables. */
+  tables = grub_efi_system_table->configuration_table;
+
+  for (i = 0; i < grub_efi_system_table->num_table_entries; i++)
+    if (grub_memcmp (&tables[i].vendor_guid, &fdt_guid, sizeof (fdt_guid)) == 0)
+      {
+	firmware_fdt = tables[i].vendor_table;
+	grub_dprintf ("linux", "found registered FDT @ %p\n", firmware_fdt);
+	break;
+      }
+
+  return firmware_fdt;
+}
+
 void
 grub_efi_fini (void)
 {