ARM: sa11x0: Use void __iomem * in MMIO accessors

MMIO accessors such as readl() and writel() want a void __iomem * for
the address. Update the BSE nanoEngine PCI driver to pass such pointers
instead of unsigned long in preparation to converting ARM to use generic
and more rigidly typed accessors.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>