mlxsw: reg: Add eth prefix to PTYS pack and unpack

We want to add Infiniband support to PTYS. In order to maintain proper
conventions, we will change pack and unpack prefix to eth.

Signed-off-by: Elad Raz <eladr@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>