qemu_get_family() needs to add LoongArch support.

Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20220705065943.2353930-1-gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>