net/mlx5: fix entry in shared Rx queues list

net/mlx5: fix entry in shared Rx queues list

The mlx5_rxq_new function creates control structure and if it from
shared group, it is inserted into the shared RXQs list.

After that, there are some validations which in case they fail, RxQ
control object is released.
In these cases, invalid pointer to the object still in the list, and
access it may cause a crash.

Move the list insertion to the end of the function where the RxQ control
object is surely valid.

Fixes: 09c2555303be ("net/mlx5: support shared Rx queue")
Cc: stable@dpdk.org
Signed-off-by: Michael Baum <michaelba@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>