net: mscc: ocelot: publish structure definitions to include/soc/mscc/ocelot.h

We will be registering another switch driver based on ocelot, which
lives under drivers/net/dsa.

Make sure the Felix DSA front-end has the necessary abstractions to
implement a new Ocelot driver instantiation. This includes the function
prototypes for implementing DSA callbacks.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>