net: dsa: Add new binding implementation

net: dsa: Add new binding implementation

The existing DSA binding has a number of limitations and problems. The
main problem is that it cannot represent a switch as a linux device,
hanging off some bus. It is limited to one CPU port. The DSA platform
device is artificial, and does not really represent hardware.

Implement a new binding which can be embedded into any type of node on
a bus to represent one switch device, and its links to other switches.

Signed-off-by: Andrew Lunn <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
Signed-off-by: David S. Miller <[email protected]>