[ARM] 4263/1: fix IXP4XX_NPE[ABC]_BASE_VIRT address

This fixs address defines for IXP4XX_NPE[ABC]_BASE_VIRT.
They are defined as (IXP4XX_PERIPHERAL_BASE_PHYS + 0x[678]000) now,
but they should be defined as (IXP4XX_PERIPHERAL_BASE_VIRT + 0x[678]000). Note PHYS vs VIRT in IXP4XX_PERIPHERAL_BASE...

Signed-off-by: Milan Svoboda <msvoboda@ra.rockwell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>