fix nandroid linkage issue

Change-Id: I36998f2e94ad1ead656c6374c551d5e02e2db219
diff --git a/nandroid.c b/nandroid.c
index 60aa564..d49cbab 100644
--- a/nandroid.c
+++ b/nandroid.c
@@ -286,7 +286,7 @@
     if (restore_boot)
     {
         ui_print("Erasing boot before restore...\n");
-        if (0 != (ret = format_device("boot")))
+        if (0 != (ret = format_volume("/boot")))
             return print_and_error("Error while formatting BOOT:!\n");
         sprintf(tmp, "%s/boot.img", backup_path);
         ui_print("Restoring boot image...\n");