ARM: realview: don't map undefined PCI registers

PCI support for realview was never merged, and trying to build realview with
CONFIG_PCI enabled fails because the constants for the mapping windows are
not defined anywhere.

This removes them from the static I/O window mapping table as a preparation
for multiplatform support.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>