net/mlx5: support Sub-Function

net/mlx5: support Sub-Function

Introduce SF support.
Similar to VF, SF on auxiliary bus is a portion of hardware PF,
no representor or bonding parameters for SF.

Devargs to support SF:
-a auxiliary:mlx5_core.sf.8,dv_flow_en=1

New global syntax to support SF:
-a bus=auxiliary,name=mlx5_core.sf.8/class=eth/driver=mlx5,dv_flow_en=1

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>