ARM: pxa: use correct __iomem annotations

This tries to clear up the confusion between integers and iomem pointers
in the marvell pxa platform. MMIO addresses are supposed to be __iomem*
values, in order to let the Linux type checking work correctly. This
patch moves the cast to __iomem as far back as possible, to the place
where the MMIO virtual address windows are defined.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>