powerpc/powernv: move dma_get_required_mask from pnv_phb to pci_controller_ops

Simplify the dma_get_required_mask call chain by moving it from pnv_phb to
pci_controller_ops, similar to commit 763d2d8df1ee ("powerpc/powernv:
Move dma_set_mask from pnv_phb to pci_controller_ops").

Previous call chain:

  0) call dma_get_required_mask() (kernel/dma.c)
  1) call ppc_md.dma_get_required_mask, if it exists. On powernv, that
     points to pnv_dma_get_required_mask() (platforms/powernv/setup.c)
  2) device is PCI, therefore call pnv_pci_dma_get_required_mask()
     (platforms/powernv/pci.c)
  3) call phb->dma_get_required_mask if it exists
  4) it only exists in the ioda case, where it points to
       pnv_pci_ioda_dma_get_required_mask() (platforms/powernv/pci-ioda.c)

New call chain:

  0) call dma_get_required_mask() (kernel/dma.c)
  1) device is PCI, therefore call pci_controller_ops.dma_get_required_mask
     if it exists
  2) in the ioda case, that points to pnv_pci_ioda_dma_get_required_mask()
     (platforms/powernv/pci-ioda.c)

In the p5ioc2 case, the call chain remains the same -
dma_get_required_mask() does not find either a ppc_md call or
pci_controller_ops call, so it calls __dma_get_required_mask().

Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index fdafbac..528cd1e 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1597,9 +1597,10 @@
 	return 0;
 }
 
-static u64 pnv_pci_ioda_dma_get_required_mask(struct pnv_phb *phb,
-					      struct pci_dev *pdev)
+static u64 pnv_pci_ioda_dma_get_required_mask(struct pci_dev *pdev)
 {
+	struct pci_controller *hose = pci_bus_to_host(pdev->bus);
+	struct pnv_phb *phb = hose->private_data;
 	struct pci_dn *pdn = pci_get_pdn(pdev);
 	struct pnv_ioda_pe *pe;
 	u64 end, mask;
@@ -3024,6 +3025,7 @@
        .window_alignment = pnv_pci_window_alignment,
        .reset_secondary_bus = pnv_pci_reset_secondary_bus,
        .dma_set_mask = pnv_pci_ioda_dma_set_mask,
+       .dma_get_required_mask = pnv_pci_ioda_dma_get_required_mask,
        .shutdown = pnv_pci_ioda_shutdown,
 };
 
@@ -3170,7 +3172,6 @@
 
 	/* Setup TCEs */
 	phb->dma_dev_setup = pnv_pci_ioda_dma_dev_setup;
-	phb->dma_get_required_mask = pnv_pci_ioda_dma_get_required_mask;
 
 	/* Setup MSI support */
 	pnv_pci_init_ioda_msis(phb);