powerpc/mpc8xxx: Add x4 DDR device support

On selected platforms, x4 DDR devices can be supported. Using x4 devices may
lower the performance, but generally they are available for higher density.

Tested on MT36JSF2G72PZ-1G9E1 RDIMM.

Signed-off-by: York Sun <yorksun@freescale.com>
6 files changed