ACPI: Only count valid srat memory structures

Otherwise you could run into:
WARN_ON in numa_register_memblks(), because node_possible_map is zero

References: https://bugzilla.novell.com/show_bug.cgi?id=757888

On this machine (ProLiant ML570 G3) the SRAT table contains:
  - No processor affinities
  - One memory affinity structure (which is set disabled)

CC: Per Jessen <per@opensuse.org>
CC: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c
index 4599c3e..4ddf497 100644
--- a/arch/x86/mm/srat.c
+++ b/arch/x86/mm/srat.c
@@ -142,23 +142,23 @@
 #endif
 
 /* Callback for parsing of the Proximity Domain <-> Memory Area mappings */
-void __init
+int __init
 acpi_numa_memory_affinity_init(struct acpi_srat_mem_affinity *ma)
 {
 	u64 start, end;
 	int node, pxm;
 
 	if (srat_disabled())
-		return;
+		return -1;
 	if (ma->header.length != sizeof(struct acpi_srat_mem_affinity)) {
 		bad_srat();
-		return;
+		return -1;
 	}
 	if ((ma->flags & ACPI_SRAT_MEM_ENABLED) == 0)
-		return;
+		return -1;
 
 	if ((ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) && !save_add_info())
-		return;
+		return -1;
 	start = ma->base_address;
 	end = start + ma->length;
 	pxm = ma->proximity_domain;
@@ -168,12 +168,12 @@
 	if (node < 0) {
 		printk(KERN_ERR "SRAT: Too many proximity domains.\n");
 		bad_srat();
-		return;
+		return -1;
 	}
 
 	if (numa_add_memblk(node, start, end) < 0) {
 		bad_srat();
-		return;
+		return -1;
 	}
 
 	node_set(node, numa_nodes_parsed);
@@ -181,6 +181,7 @@
 	printk(KERN_INFO "SRAT: Node %u PXM %u [mem %#010Lx-%#010Lx]\n",
 	       node, pxm,
 	       (unsigned long long) start, (unsigned long long) end - 1);
+	return 0;
 }
 
 void __init acpi_numa_arch_fixup(void) {}