[ARM] Orion: add RD88F6183AP-GE support

The RD88F6183AP-GE is an access point reference design for the
88F6183 SoC, with a 88E6161 six-port gigabit ethernet switch with
five PHYs (providing 1 WAN and 4 LAN ports and an interface to the
CPU), and a mini-PCIe slot for a wireless card.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>