[POWERPC] Add support for the mpc832x mds board

Add support for MPC832x MDS evaluation board.

This patch depends on the 8360+QE lib patches by Leo.

The MPC832x processors (MPC8323E, MPC8323, MPC8321E, MPC8321) sport
the e300c2 core plus a QUICC Engine (QE).  This patch adds support for
the 832x MDS evaluation board.

The 832x MDS dts and defconfig files are pending more tests.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>