[PATCH] powerpc/64s: power4 nap fixup in C

[Nicholas Piggin]

Excerpts from Andreas Schwab's message of April 6, 2021 2:40 am:
> On Apr 05 2021, Nicholas Piggin wrote:
> 
>> I worked it out. There was a window where it could take another 
>> interrupt before the first one adjusts the nip.
>>
>> I managed to trigger it in qemu and this version fixed it.
> 
> Works for me as well.

Aha, thank you for testing it. Finally fixed it. I'll resubmit the
patch.

Thanks,
Nick