nvme: Add SMART WARNING for persistent memory region

[imp]

Summary

NVME 2.0 added persistent memory regions, and this bit reports critical
warnings / errors with those regions.

Sponsored by: Netflix

[mav]

I wonder if there are any namespace-specific events? I remember NVMe specs allow per-namespace SMART, but I don't remember much details now.

[imp]

In D44213#1008990, @mav wrote:

I wonder if there are any namespace-specific events? I remember NVMe specs allow per-namespace SMART, but I don't remember much details now.

I don't recall seeing that, but I'll take a look. But for SMART events, I didn't see any when I just checked. I think they come in on the namespace change page... Which likely also needs work.