net/mlx5: E-Switch, Mark miss packets with new chain id mapping

Currently, if we miss in hardware after jumping to some chain,
we continue in chain 0 in software. This is wrong, and with the new
tc skb extension we can now restore the chain id on the skb, so
tc can continue with in the correct chain.

To restore the chain id in software after a miss in hardware, we create
a register mapping from 32bit chain ids to 16bit of reg_c0 (that
survives loopback), to 32bit chain ids. We then mark packets that
miss on some chain with the current chain id mapping on their reg_c0
field. Using this mapping, we will support up to 64K concurrent
chains.

This register survives loopback and gets to the CQE on flow_tag
via the eswitch restore rules.

In next commit, we will reverse the mapping we got on the CQE
to a chain id and tell tc to continue in the sw chain where we
left off via the tc skb extension.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Oz Shlomo <ozsh@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>