ARM: Kirkwood: DIR665: Instantiate Distributed Switch Architecture

The DIR665 has an 8 port Ethernet Switch, a Marvell mv88e6171. Add a
DSA node in DT, to instantiate DSA support for the 4 back panel ports,
the Internet port, and the port to the CPU which is connected to eth0.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lkml.kernel.org/r/1414793613-11798-3-git-send-email-andrew@lunn.ch
Signed-off-by: Jason Cooper <jason@lakedaemon.net>