net/mlx5: E-switch, Create QoS on demand

Don't create eswitch QoS (root TSAR) on switch mode change. Create it on
first child TSAR object creation - vport or rate group. Keep track
root TSAR references and release root TSAR with last object deletion.
No need to check for QoS is enabled when installing tc matchall filter.
Remove related helper function due to no users of it.

Signed-off-by: Dmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>