i40evf: set adapter state on reset failure

If a reset fails to complete, the driver gets its affairs in order and
awaits the cold solace of rmmod. Unfortunately, it was not properly
setting the adapter state, which would cause a panic on rmmod, instead
of the desired surcease.

Set the adapter state to DOWN in this case, and avoid a panic.

Change-ID: I6fdd9906da52e023f8dc744f7da44b5d95278ca9
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>