powerpc/fsl-pci: Keep PCI SoC controller registers in pci_controller

Move to keeping the SoC registers that control and config the PCI
controllers on FSL SoCs in the pci_controller struct.  This allows us to
not need to ioremap() the registers in multiple different places that
use them.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>