sw64: kvm: fix inconsitent timing metrics

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I73O8P



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Guest os programs next event based on ticks, which is inconsistent
with expired time of hypervisor's hrtimer based on nanosencods.

This patch converts virtual clock event ticks to nanoseconds(by
host initial CPU frequency temporarily) to fix it.

Signed-off-by: Min Fanlei <minfanlei@wxiat.com>
Reviewed-by: He Sheng <hesheng@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>