LoongArch: LSVZ: Support PV IPI to reduce VM exit

LoongArch inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I76XVK



--------------------------------

PV IPI with less VM exit can improve performance than
iocsr emulation when sending ipi interrupt to multi cpus.

This patch supports:
1. sending PV IPI by hypercall
2. recording and updating steal time for VM

Change-Id: Ia3ce493b83c067cc9e7c66b3094e4d87ff630f1d
Signed-off-by: zhoumin <zhoumin@loongson.cn>