net/mlx5: validate hash Rx queue pointer
net/mlx5: validate hash Rx queue pointer

Implementation of mlx5_hrxq_get() tries to get pointer to a hrxq
object, by reusing an existing hrxq, or creating a new one.
There is no check of the obtained pointer, so using it might result
in error.

This patch adds check of the pointer before using it, and return 0
if the pointer is NULL to indicate error.

Fixes: e1592b6c4dea ("net/mlx5: make Rx queue thread safe")
Cc: stable@dpdk.org

Signed-off-by: Dekel Peled <f1921780d3213ef78965aec36396441d9bf8894c@nvidia.com>
Acked-by: Matan Azrad <6969f5f553ad7652679a585a85d7321babc90464@nvidia.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk