ACPI / numa: Use __weak, not the gcc-specific version

Use "__weak" instead of the gcc-specific "__attribute__ ((weak))".
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/numa.c

@@ -193,7 +193,7 @@ static int __init acpi_parse_slit(struct acpi_table_header *table)
 	return 0;
 }
 
-void __init __attribute__ ((weak))
+void __init __weak
 acpi_numa_x2apic_affinity_init(struct acpi_srat_x2apic_cpu_affinity *pa)
 {
 	printk(KERN_WARNING PREFIX