target/loongarch: Add steal time support on migration

target/loongarch: Add steal time support on migration

With pv steal time supported, VM machine needs get physical address
of each vcpu and notify new host during migration. Here two
functions kvm_get_stealtime/kvm_set_stealtime, and guest steal time
physical address is only updated on KVM_PUT_FULL_STATE stage.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20240930064040.753929-1-maobibo@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>