powerpc/cell: Fix iommu breakage caused by controller_ops change

The recent patch to convert cell to use pci_controller_ops had a small
bug which broke machines using an iommu.

The set of phb->controller_ops was added after the check for name !=
"pci", meaning pcix/pcie PHBs weren't getting their ops set correctly.

Fixes: 9c1368fc ("powerpc/cell: Move controller ops from ppc_md to controller_ops")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>