restore: return -1 if fail

In cr_dump_tasks() we expect restore_root_task to return < 0 if
error ocures.
Signed-off-by: Ruslan Kuprieiev <kupruser@gmail.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -1779,7 +1779,7 @@ out_kill:
 out:
 	__restore_switch_stage(CR_STATE_FAIL);
 	pr_err("Restoring FAILED.\n");
-	return 1;
+	return -1;
 }
 
 static int prepare_task_entries(void)