sw64: perf: fix PMI with no event

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5XTIW



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For perf disable PMU, this then presents the following error
condition in processes schedule:

Process A		Process B

Disable irq
<PMC overflow>
Disable PMU
			Enable irq
			<PMI comes>
			   ->sw64_perf_event_irq_handler()

When irq is disabled, PMC may still overflow then a PMI triggers.
After another process is scheduled and irq is enabled, this PMI
will raise immediately.

To avoid this, clear interrupt flag in hmcode when it disable PMU.
However, in kernel, events that do not exist will return directly.

Signed-off-by: He Chuyue <hechuyue@wxiat.com>
Reviewed-by: He Sheng <hesheng@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>