We are seeing an issue where setting the MAC address on iavf fails with
EAGAIN after the 2.5s timeout expires in iavf_set_mac().

There is the following deadlock scenario:

iavf_set_mac(), holding rtnl_lock, waits on:
  iavf_watchdog_task (within iavf_wq) to send a message to the PF,
 and
  iavf_adminq_task (within iavf_wq) to receive a response from the PF.
In this adapter state (>=__IAVF_DOWN), these tasks do not need to take
rtnl_lock, but iavf_wq is a global single-threaded workqueue, so they
may get stuck waiting for another adapter's iavf_watchdog_task to run
iavf_init_config_adapter(), which does take rtnl_lock.

The deadlock resolves itself by the timeout in iavf_set_mac(),
which results in EAGAIN returned to userspace.

Let's break the deadlock loop by changing iavf_wq into a per-adapter
workqueue, so that one adapter's tasks are not blocked by another's.

Fixes: 35a2443d ("iavf: Add waiting for response from PF in set mac")
Co-developed-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>