natsemi: fix MMIO for PPC 44x platforms

The driver stores the PCI resource address into 'unsigned long' variable before
calling ioremap()  on it. This warrants a kernel oops when the registers are
accessed on PPC 44x platforms which (being 32-bit) have PCI memory space mapped
beyond 4 GB.

The arch/ppc/ kernel has a fixup in ioremap() that creates an illusion of the
PCI memory resources are mapped below 4 GB, but arch/powerpc/ code got rid of
this trick, having instead CONFIG_RESOURCES_64BIT enabled.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>