i40e: better error reporting for nvmupdate

Make sure we return EBUSY while finishing up a reset, and add a few bits
for better debug messages.

Change-ID: I23f6c28a8d96d7aa171abcc265737cec7826c292
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>