net/ice/base: update VSI handle to remaining VSI

net/ice/base: update VSI handle to remaining VSI

When removing VSI from VSI list, if only one VSI left, we need
to downgrade a switch rule's action from "to VSI LIST" to "to VSI",
So, needs to update the VSI handle to the last remaining VSI for the
new action but not the first VSI be added to the list.

Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Signed-off-by: Paul M Stillwell Jr <paul.m.stillwell.jr@intel.com>
Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Acked-by: Qiming Yang <qiming.yang@intel.com>