loongarch/kvm: Fixed extioi hardware emulation bugs

LoongArch inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7QOYY



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When the extioi controller is enabled,
the data in the extioi controller should
not be emptied.Otherwise, the interrupt triggered
when kdump re-enters the kernel will cause the register state
in the extioi controller to be inconsistent with the ESTAT register
state after extioi is enabled, and finally cause the extended interrupt
to be triggered all the time.

Signed-off-by: xianglai li <lixianglai@loongson.cn>
(cherry picked from commit 99bf1b35)