net/mlx5: fix port shared data reference count

net/mlx5: fix port shared data reference count

When probe a representor, tag cache hash table and modification cache
hash table allocated memory upon each port, overwrote previous existing
cache in shared context data.

This patch moves reference check of shared data prior to hash table
allocation to avoid such issue.

Fixes: 6801116688fe ("net/mlx5: fix multiple flow table hash list")
Fixes: 1ef4cdef2682 ("net/mlx5: fix flow tag hash list conversion")
Cc: stable@dpdk.org
Acked-by: Matan Azrad <matan@nvidia.com>
Signed-off-by: Xueming Li <xuemingl@nvidia.com>