[POWERPC] Pass the pci_controller into pci_exclude_device

There are times that we need to know which controller we are on to decide
how to exclude devices properly.  We now pass the pci_controller that we
are going to use down to the pci_exclude_device function. This will
greatly simplify being able to exclude the PHBs in multiple controller
setups.

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