PCI: iproc: Fix NULL pointer dereference for BCMA

With the inbound DMA mapping supported added, the iProc PCIe driver
parses DT property "dma-ranges" through call to
"of_pci_dma_range_parser_init()". In the case of BCMA, this results in a
NULL pointer deference due to a missing of_node.

Fix this by adding a guard in pcie-iproc-platform.c to only enable the
inbound DMA mapping logic when DT property "dma-ranges" is present.

Fixes: dd9d4e7498de3 ("PCI: iproc: Add inbound DMA mapping support")
Reported-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Rafał Miłecki <rafal@milecki.pl>
cc: <stable@vger.kernel.org> # 4.10+
diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c
index 935909b..7583606 100644
--- a/drivers/pci/host/pcie-iproc.c
+++ b/drivers/pci/host/pcie-iproc.c
@@ -1378,9 +1378,11 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
 		}
 	}
 
-	ret = iproc_pcie_map_dma_ranges(pcie);
-	if (ret && ret != -ENOENT)
-		goto err_power_off_phy;
+	if (pcie->need_ib_cfg) {
+		ret = iproc_pcie_map_dma_ranges(pcie);
+		if (ret && ret != -ENOENT)
+			goto err_power_off_phy;
+	}
 
 #ifdef CONFIG_ARM
 	pcie->sysdata.private_data = pcie;