iavf: get rid of the crit lock

In the Linux kernel, the following vulnerability has been resolved:

iavf: get rid of the crit lock

Get rid of the crit lock.

That frees us from the error prone logic of try_locks.

Thanks to netdev_lock() by Jakub it is now easy, and in most cases we were

protected by it already - replace crit lock by netdev lock when it was not

the case.

Lockdep reports that we should cancel the work under crit_lock [splat1],

and that was the scheme we have mostly followed since [1] by Slawomir.

But when that is done we still got into deadlocks [splat2]. So instead

we should look at the bigger problem, namely "weird locking/scheduling"

of the iavf. The first step to fix that is to remove the crit lock.

I will followup with a -next series that simplifies scheduling/tasks.

Cancel the work without netdev lock (weird unlock+lock scheme),

to fix the [splat2] (which would be totally ugly if we would kept

the crit lock).

Extend protected part of iavf_watchdog_task() to include scheduling

more work.

Note that the removed comment in iavf_reset_task() was misplaced,

it belonged to inside of the removed if condition, so it's gone now.

[splat1] - w/o this patch - The deadlock during VF removal:

WARNING: possible circular locking dependency detected

sh/3825 is trying to acquire lock:

((work_completion)(&(&adapter->watchdog_task)->work)){+.+.}-{0:0}, at: start_flush_work+0x1a1/0x470

but task is already holding lock:

(&adapter->crit_lock){+.+.}-{4:4}, at: iavf_remove+0xd1/0x690 [iavf]

which lock already depends on the new lock.

[splat2] - when cancelling work under crit lock, w/o this series,

see [2] for the band aid attempt

WARNING: possible circular locking dependency detected

sh/3550 is trying to acquire lock:

((wq_completion)iavf){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x26/0x90

but task is already holding lock:

(&dev->lock){+.+.}-{4:4}, at: iavf_remove+0xa6/0x6e0 [iavf]

which lock already depends on the new lock.

[1] fc2e6b3b132a ("iavf: Rework mutexes for better synchronisation")

[2] https://github.com/pkitszel/linux/commit/52dddbfc2bb60294083f5711a158a