x86, smp: refactor ->inquire_remote_apic() methods

Nothing exciting - a few subarches dont want APIC remote reads to
be performed - the others are content with the default method.

 - extend the generic code to handle NULL methods

 - clear out dummy methods and replace them with NULL

 - clean up: remove wrapper macros, etc.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mach-generic/default.c b/arch/x86/mach-generic/default.c
index b004257..c12dd23 100644
--- a/arch/x86/mach-generic/default.c
+++ b/arch/x86/mach-generic/default.c
@@ -92,5 +92,5 @@
 
 	.smp_callin_clear_local_apic	= NULL,
 	.store_NMI_vector		= NULL,
-	.inquire_remote_apic		= inquire_remote_apic,
+	.inquire_remote_apic		= default_inquire_remote_apic,
 };