i40e: clear NVM update state on ethtool test

Once in a great while the NVMUpdate tools and the driver get out
of phase with each other.  This gives us a way to reset things
without having to unload the driver.

Change-ID: I353f688236249a666a90ba3e7233e0ed8c1a04e9
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>