powerpc/pci: add dma_set_mask to pci_controller_ops

Some systems only need to deal with DMA masks for PCI devices.
For these systems, we can avoid the need for a platform hook and
instead use a pci controller based hook.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/pci-bridge.h

@@ -36,6 +36,8 @@ struct pci_controller_ops {
 					  int nvec, int type);
 	void		(*teardown_msi_irqs)(struct pci_dev *dev);
 #endif
+
+	int             (*dma_set_mask)(struct pci_dev *dev, u64 dma_mask);
 };
 
 /*