x86: add dummy acpi_numa_processor_affinity_init() implementation on 32-bit

allow CONFIG_ACPI_NUMA builds to succeed.
diff --git a/arch/x86/mm/discontig_32.c b/arch/x86/mm/discontig_32.c
index d28987a..bb8544a 100644
--- a/arch/x86/mm/discontig_32.c
+++ b/arch/x86/mm/discontig_32.c
@@ -462,4 +462,9 @@
 void __init acpi_numa_slit_init(struct acpi_table_slit *slit)
 {
 }
+
+void __init
+acpi_numa_processor_affinity_init(struct acpi_srat_cpu_affinity *pa)
+{
+}
 #endif