[PATCH] powerpc: Migrate Xilinx Vertex support from the OCP bus to the platfom bus.

This patch only deals with the serial port definitions as there is no
support for any other xilinx IP cores in the kernel tree at the moment.

Board specific configuration moved out of virtex.[ch] and into the
xparameters.h wrapper.

This also prepares for the transition to the flattened device tree model.
When the bootloader provides a device tree generated from an xparameters.h
files, the kernel will no longer need xparameters/*.  The platform bus will
get populated with data from the device tree, and the device drivers will
be automatically connected to the devices.  Only the bootloader (or
ppcboot) will need xparameters directly.

Signed-off-by: Grant C. Likely <grant.likely@secretlab.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>