i40e: Fix dependencies in the i40e driver on configfs

Module dependencies are broken in the case where CONFIG_I40E=y and
CONFIG_CONFIGFS_FS=m.  This fixes the broken dependency.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>