loongarch: Add auxiliary files

Add support for manipulating architectural cache and timers, and EFI
memory maps.

Signed-off-by: Zhou Yang <zhouyang@loongson.cn>
Signed-off-by: Xiaotian Wu <wuxiaotian@loongson.cn>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/kern/loongarch64/cache_flush.S

@@ -0,0 +1,33 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2023 Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/symbol.h>
+
+	.file	"cache_flush.S"
+	.text
+/*
+ * No further work to do because cache consistency is maintained by hardware on
+ * LoongArch.
+ */
+FUNCTION(grub_arch_clean_dcache_range)
+	dbar 0
+	jr $ra
+
+FUNCTION(grub_arch_invalidate_icache_range)
+	ibar 0
+	jr $ra