x86: unify genapic code, unify subarchitectures, remove old subarchitecture code, xapic fix

xapic fix for 32bit platform with less than 8 cpu's.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/probe_32.c

@@ -113,7 +113,7 @@ struct genapic apic_default = {
 	.cpu_mask_to_apicid_and		= default_cpu_mask_to_apicid_and,
 
 	.send_IPI_mask			= default_send_IPI_mask,
-	.send_IPI_mask_allbutself	= NULL,
+	.send_IPI_mask_allbutself	= default_send_IPI_mask_allbutself,
 	.send_IPI_allbutself		= default_send_IPI_allbutself,
 	.send_IPI_all			= default_send_IPI_all,
 	.send_IPI_self			= NULL,