Add the maintainer information for the LoongArch (LA or LArch for short)
architecture.
Reviewed-by: NGuo Ren <guoren@kernel.org>
Reviewed-by: NJiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: NWANG Xuerui <git@xen0n.name>
Signed-off-by: NHuacai Chen <chenhuacai@loongson.cn>