net/ice/base: fix issues around move nodes

net/ice/base: fix issues around move nodes

1. Fixed the max children check when moving the last(8th) children. This
   allows the parent node to hold 8 children instead of 7.
2. Check whether the VSI is already part of the given aggregator subtree
   before moving it.

Fixes: 29a0c11489ef ("net/ice/base: clean code")
Cc: stable@dpdk.org
Signed-off-by: Victor Raj <victor.raj@intel.com>
Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Acked-by: Qiming Yang <qiming.yang@intel.com>