i40evf: lower message level

We see this message regularly on VF reset or unload (which invokes a
reset). It's essentially meaningless unless it's happening constantly.
To prevent consternation, lower the log level to debug so it's not seen
under normal circumstance.

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>