kvm: arm64: make ID registers configurable

hulk inclusion
category: feature
bugzilla: 48052
CVE: NA

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It's time to make ID registers configurable.  When userspace (but not
guest) want to set the values of ID registers, save the value in
kvm_arch_vcpu so that guest can read the modified values.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Peng Liang <liangpeng10@huawei.com>
Reviewed-by: Zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>