ARM: Kirkwood: Add DT description of QNAP 419

Re-implement the Marvell Kirkwood ts41x-setup.c in DT.

As with the QNAP 119, there are two variants, depending on which SoC
has been used. They differ on Ethernet PHY addresses and number of
PCIe busses.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Ian Campbell <ijc@hellion.org.uk> (kirkwood-ts419-6281.dtb)
Signed-off-by: Jason Cooper <jason@lakedaemon.net>