ena: Add reset reason for missing admin interrupt

[osamaabb_amazon.com]

Summary

There can be cases when we trigger reset if an admin interrupt
is missing.
In order to identify this use-case specifically,
this commit adds a new reset reason.

Approved by: cperciva
MFC after: 2 weeks
Sponsored by: Amazon, Inc.

[cperciva]

this commit adds a new reset reason.

I see a new reason defined in ena_regs_defs.h but it doesn't look like it's actually being used?

[osamaabb_amazon.com]

In D46346#1064454, @cperciva wrote:

this commit adds a new reset reason.

I see a new reason defined in ena_regs_defs.h but it doesn't look like it's actually being used?

Right, this is the ena-com commit, this reset reason will be used a latter commit down this patch series