x86, apic: get rid of *_APIC_ID_MASK definitions

Impact: cleanup

Remove the *_APIC_ID_MASK subarch definitions and move them straight
to the genapic driver initialization code.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mach-generic/bigsmp.c b/arch/x86/mach-generic/bigsmp.c
index 1f4ad4f..ee52c59 100644
--- a/arch/x86/mach-generic/bigsmp.c
+++ b/arch/x86/mach-generic/bigsmp.c
@@ -92,7 +92,7 @@
 
 	.get_apic_id			= bigsmp_get_apic_id,
 	.set_apic_id			= NULL,
-	.apic_id_mask			= BIGSMP_APIC_ID_MASK,
+	.apic_id_mask			= 0xFF << 24,
 
 	.cpu_mask_to_apicid		= cpu_mask_to_apicid,
 	.cpu_mask_to_apicid_and		= cpu_mask_to_apicid_and,