PCI: iproc: Fix a leaked reference by adding missing of_node_put()

The call to of_parse_phandle() returns a node pointer with refcount
incremented thus it must be explicitly decremented after the last
usage.

iproc_msi_init() also calls of_node_get() to increase refcount:

proc_msi_init()
 -> iproc_msi_alloc_domains()
  -> pci_msi_create_irq_domain()
   -> msi_create_irq_domain()
    -> irq_domain_create_linear()
     -> __irq_domain_add()

so irq_domain will not be affected when it is released.

Detected by coccinelle with the following warnings:
  ./drivers/pci/controller/pcie-iproc.c:1323:3-9: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 1299, but without a corresponding object release within this function.
  ./drivers/pci/controller/pcie-iproc.c:1330:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 1299, but without a corresponding object release within this function.
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: linux-pci@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org

drivers/pci/controller/pcie-iproc.c

@@ -1320,14 +1320,18 @@ static int iproc_pcie_msi_enable(struct iproc_pcie *pcie)
 	if (pcie->need_msi_steer) {
 		ret = iproc_pcie_msi_steer(pcie, msi_node);
 		if (ret)
-			return ret;
+			goto out_put_node;
 	}
 
 	/*
 	 * If another MSI controller is being used, the call below should fail
 	 * but that is okay
 	 */
-	return iproc_msi_init(pcie, msi_node);
+	ret = iproc_msi_init(pcie, msi_node);
+
+out_put_node:
+	of_node_put(msi_node);
+	return ret;
 }
 
 static void iproc_pcie_msi_disable(struct iproc_pcie *pcie)