ice: create new Tx scheduler nodes for new queues only

ice: create new Tx scheduler nodes for new queues only

The current implementation of the Tx scheduler tree attempts
to create nodes for all Tx queues, ignoring the fact that some
queues may already exist in the tree. For example, if the VSI
already has 128 Tx queues and the user requests for 16 new queues,
the Tx scheduler will compute the tree for 272 queues (128 existing
queues + 144 new queues), instead of 144 queues (128 existing queues
and 16 new queues).
Fix that by modifying the node count calculation algorithm to skip
the queues that already exist in the tree.

Fixes: 5513b920a4f7 ("ice: Update Tx scheduler tree for VSI multi-Tx queue support")
Reviewed-by: Dawid Osuchowski <dawid.osuchowski@linux.intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Michal Kubiak <michal.kubiak@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Jesse Brandeburg <jbrandeburg@cloudflare.com>
Tested-by: Saritha Sanigani <sarithax.sanigani@intel.com> (A Contingent Worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>