fm10k: prepare_for_reset() when we lose PCIe Link

If we lose PCIe link, such as when an unannounced PFLR event occurs, or
when a device is surprise removed, we currently detach the device and
close the netdev. This unfortunately leaves a lot of things still
active, such as the msix_mbx_pf IRQ, and Tx/Rx resources.

This can cause problems because the register reads will return
potentially invalid values which may result in unknown driver behavior.

Begin the process of resetting using fm10k_prepare_for_reset(), much in
the same way as the suspend and resume cycle does. This will attempt to
shutdown as much as possible, in order to prevent possible issues.

A naive implementation for this has issues, because there are now
multiple flows calling the reset logic and setting a reset bit. This
would cause problems, because the "re-attach" routine might call
fm10k_handle_reset() prior to the reset actually finishing. Instead,
we'll add state bits to indicate which flow actually initiated the
reset.

For the general reset flow, we'll assume that if someone else is
resetting that we do not need to handle it at all, so it does not need
its own state bit. For the suspend case, we will simply issue a warning
indicating that we are attempting to recover from this case when
resuming.

For the detached subtask, we'll simply refuse to re-attach until we've
actually initiated a reset as part of that flow.

Finally, we'll stop attempting to manage the mailbox subtask when we're
detached, since there's nothing we can do if we don't have a PCIe
address.

Overall this produces a much cleaner shutdown and recovery cycle for
a PCIe surprise remove event.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>