x86: remove various unused subarch hooks

Impact: remove dead code

Remove:

 - pre_setup_arch_hook()
 - mca_nmi_hook()

If needed they can be added back via an x86_quirk handler.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/mca_32.c

@@ -474,6 +474,4 @@ void __kprobes mca_handle_nmi(void)
 	 * adapter was responsible for the error.
 	 */
 	bus_for_each_dev(&mca_bus_type, NULL, NULL, mca_handle_nmi_callback);
-
-	mca_nmi_hook();
-} /* mca_handle_nmi */
+}