net/mlx5: convert tag resource to indexed

net/mlx5: convert tag resource to indexed

This commit convert tag resource to indexed.

As tag resources are add in the hash list, to avoid introduce
performance issue and keep the hash list, only the tag resource memory
is allocated from indexed memory. The resources is still added to the
hash list. Add four bytes index in the tag resource struct and change
the tag resources in the flow handle from pointer to uint32_t seems be
no benefit for tag resource, but it saves memory for flows without tag
action. And also for sub flows share one tag action resource.

Signed-off-by: Suanming Mou <suanmingm@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>