sw64: kvm: handle ldl_u and stl_u when exit mmio

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



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In guest os, ldl_u and stl_u may access mmio in some cases, so we
have to decode and handle this issue when exit mmio.

Signed-off-by: Lu Feifei <lufeifei@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>