ice: allow creating VFs for !CONFIG_NET_SWITCHDEV

Currently for !CONFIG_NET_SWITCHDEV kernel builds it is not possible to
create VFs properly as call to ice_eswitch_configure() returns
-EOPNOTSUPP for us. This is because CONFIG_ICE_SWITCHDEV depends on
CONFIG_NET_SWITCHDEV.

Change the ice_eswitch_configure() implementation for
!CONFIG_ICE_SWITCHDEV to return 0 instead -EOPNOTSUPP and let
ice_ena_vfs() finish its work properly.

CC: Grzegorz Nitka <grzegorz.nitka@intel.com>
Fixes: 1a1c40df ("ice: set and release switchdev environment")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>