hw/vexpress.c: Make motherboard peripheral memory map table-driven

hw/vexpress.c: Make motherboard peripheral memory map table-driven

Pull the addresses used for mapping motherboard peripherals into
memory out into a table. This will allow us to simply provide a
second table to implement the "Cortex-A Series" memory map used by
the A15 variant of Versatile Express, as well as the current
"Legacy" map used by A9.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Andreas Färber <afaerber@suse.de>