powerpc/85xx: introduce support for the Freescale / iVeia P1022RDK

The Freescale / iVeia P1022RDK reference board is a small-factor board
with a Freescale P1022 SOC.  It includes:

1) 512 MB 64-bit DDR3-800 (max) memory
2) 8MB SPI serial flash memory for boot loader
3) Bootable 4-bit SD/MMC port
4) Two 10/100/1000 Ethernet connectors
5) One SATA port
6) Two USB ports
7) One PCIe x4 slot
8) DVI video connector
9) Audio input and output jacks, powered by a Wolfson WM8960 codec.

Unlike the P1022DS, the P1022RDK does not have any localbus devices,
presumably because of the localbus / DIU multiplexing restriction of
the P1022 SOC.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>