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>

arch/x86/kernel/smpboot.c

@@ -876,8 +876,8 @@ do_rest:
 			else
 				/* trampoline code not run */
 				printk(KERN_ERR "Not responding.\n");
-			if (get_uv_system_type() != UV_NON_UNIQUE_APIC)
-				inquire_remote_apic(apicid);
+			if (apic->inquire_remote_apic)
+				apic->inquire_remote_apic(apicid);
 		}
 	}