ixgbe: Apply EEE policy through serialized initialization

[kbowling]

Summary

Originally authored by Tim Pletcher <[e-mail]>, with my additions

The EEE sysctl calls if_init() with an ifnet where iflib expects its
context. On an E610-XT2, writing eee_state can therefore block indefinitely
in sx_xlock() and corrupt if_broadcastaddr, causing broadcasts to use the
wrong destination address.

Cache the requested policy under the iflib context lock and request a
reset through the admin task if the interface is still administratively
up. Recheck the setting after copying in the sysctl value so concurrent
writers do not act on stale state. Identical writes remain no-ops.

Replay EEE after hardware reset and PHY power-up, before enabling queues.
This also applies settings saved while down or suspended. Log EEE replay
failures and retain the requested policy for subsequent initialization.

On E610, skip Set PHY Config when the active EEE mask already matches,
avoiding unnecessary link restarts during unrelated initialization. Allow
bounded retries of Set PHY Config only on an explicit firmware busy
response, including when the preceding PHY power-up is still completing.

Document the requested-setting readback, asynchronous application, retry
behavior, and recovery-mode restrictions.

PR:             300670
MFC after:      1 week
Sponsored by:   BBOX.io
Co-authored-by: Kevin Bowling <[e-mail]>

[kgalazka]

sys/dev/ixgbe/if_ix.c

6334–6339

I think speed check should stay in some way for a case when speed was overridden by user.

6342–6346

I wonder if this won't be confusing for an user, when physical port is shared with BMC and because of that always kept in active state by E610 FW. Maybe make it a conditional call instead of removing?