sw64: add support for emulator running mode

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56WV8



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We distinguish the running mode of emulator from guest by EMUL_FLAG
according to the related changes of qemu.

Signed-off-by: Min Fanlei <minfanlei@wxiat.com>

Signed-off-by: Gu Zitao <guzitao@wxiat.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>