ibmvnic: Updated reset handling

The ibmvnic driver has multiple handlers for resetting the driver
depending on the reason the reset is needed (failover, lpm,
fatal erors,...). All of the reset handlers do essentially the same
thing, this patch moves this work to a common reset handler.

By doing this we also allow the driver to better handle situations
where we can get a reset while handling a reset.

The updated reset handling works by adding a reset work item to the
list of resets and then scheduling work to perform the reset. This
step is necessary because we can receive a reset in interrupt context
and we want to handle the reset out of interrupt context.

Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>