powerpc/pseries: Fix regression on PCI link speed

Commit 5091f0c (powerpc/pseries: Fix PCIE link speed endian issue)
introduced a regression on the PCI link speed detection using the
device-tree property. The ibm,pcie-link-speed-stats property is composed
of two 32-bit integers, the first one being the maxinum link speed and
the second the current link speed. The changes introduced by the
aforementioned commit are considering just the first integer.

Fix this issue by changing how the property is accessed, using the
helper functions to properly access the array of values. The explicit
byte swapping is not needed anymore here, since it's done by the helper
functions.

Signed-off-by: Kleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/pseries/pci.c

@@ -113,7 +113,8 @@ int pseries_root_bridge_prepare(struct pci_host_bridge *bridge)
 {
 	struct device_node *dn, *pdn;
 	struct pci_bus *bus;
-	const __be32 *pcie_link_speed_stats;
+	u32 pcie_link_speed_stats[2];
+	int rc;
 
 	bus = bridge->bus;
 
@@ -122,20 +123,21 @@ int pseries_root_bridge_prepare(struct pci_host_bridge *bridge)
 		return 0;
 
 	for (pdn = dn; pdn != NULL; pdn = of_get_next_parent(pdn)) {
-		pcie_link_speed_stats = of_get_property(pdn,
-			"ibm,pcie-link-speed-stats", NULL);
-		if (pcie_link_speed_stats)
+		rc = of_property_read_u32_array(pdn,
+				"ibm,pcie-link-speed-stats",
+				&pcie_link_speed_stats[0], 2);
+		if (!rc)
 			break;
 	}
 
 	of_node_put(pdn);
 
-	if (!pcie_link_speed_stats) {
+	if (rc) {
 		pr_err("no ibm,pcie-link-speed-stats property\n");
 		return 0;
 	}
 
-	switch (be32_to_cpup(pcie_link_speed_stats)) {
+	switch (pcie_link_speed_stats[0]) {
 	case 0x01:
 		bus->max_bus_speed = PCIE_SPEED_2_5GT;
 		break;
@@ -147,7 +149,7 @@ int pseries_root_bridge_prepare(struct pci_host_bridge *bridge)
 		break;
 	}
 
-	switch (be32_to_cpup(pcie_link_speed_stats)) {
+	switch (pcie_link_speed_stats[1]) {
 	case 0x01:
 		bus->cur_bus_speed = PCIE_SPEED_2_5GT;
 		break;