RealView: Make more vmalloc space by changing IO_ADDRESS

Since boards like PB11MPCore have 512MB of RAM and 128MB of flash, the
virtual space is short on vmalloc memory and mapping the flash fails.
This patch changes the IO_ADDRESS so that static mappings start at
0xfc000000 and moves the PCI virtual addresses higher up. The new
VMALLOC_END is set to 0xf8000000 (512MB higher than the old value).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>