mpt(4) integrated RAID event message improvements

Hi,

I have a Sun Fire V245 with an mpt(4) with integrated RAID.  On attach it
would generate messages like:

  mpt2: Unknown async event: 0xb000000

These were messages from the integrated RAID about RAID volume status
(but the event was byte-swapped because it's a BE machine) and we didn't
handle them.

I've committed a change to parse these messages and display them:

  https://mail-index.netbsd.org/source-changes/2026/07/07/msg162920.html

So, if you have mpt with integrated RAID, you should now see messages like:

  mpt2: Integrated RAID Event: volume 0 status: optimal, enabled
  mpt2: Integrated RAID Event: volume 2 status: missing, enabled, inactive

at attach time and also when RAID events happen, rather than the unknown
async event message.

Regards,

Julian

PS.  I also see:

  mpt2: Phy 0: Link Status Unknown

for each RAID volume or (standalone) disk but it doesn't look like the
drive or RAID number is encoded as we expect in the event message, so we
always print "Phy 0".

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