sw64: fix printk method for guest os

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



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Output kernel log through the specified IO address is required by
qemu, and this method is not required by guest.

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>