app/testpmd: add parameter for shared Rx queue

app/testpmd: add parameter for shared Rx queue

Adds "--rxq-share=X" parameter to enable shared RxQ.

Rx queue is shared if device supports, otherwise fallback to standard
RxQ.

Shared Rx queues are grouped per X ports. X defaults to UINT32_MAX,
implies all ports join share group 1. Queue ID is mapped equally with
shared Rx queue ID.

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>