net/mlx5: restrict Rx queue array access to boundary

net/mlx5: restrict Rx queue array access to boundary

The mlx5_rxq_get() function gets RxQ index and return RxQ priv
accordingly.

When it gets an invalid index, it accesses out of array bounds which
might cause undefined behavior.

This patch adds a check for invalid indexes before accessing to array.

Fixes: 0cedf34da78f ("net/mlx5: move Rx queue reference count")
Cc: stable@dpdk.org
Signed-off-by: Michael Baum <michaelba@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>