net/mlx5: support shared Rx queue

net/mlx5: support shared Rx queue

This patch introduces shared RxQ. All shared Rx queues with same group
and queue ID share the same rxq_ctrl. Rxq_ctrl and rxq_data are shared,
all queues from different member port share same WQ and CQ, essentially
one Rx WQ, mbufs are filled into this singleton WQ.

Shared rxq_data is set into device Rx queues of all member ports as
RxQ object, used for receiving packets. Polling queue of any member
ports returns packets of any member, mbuf->port is used to identify
source port.

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