x86, irq: don't call mp_config_acpi_gsi() if update_mptable is not enabled

Len expressed concern that the update_mptable feature has
side-effects on the ACPI code.

Make it sure explicitly that the code only ever gets called if
the (default disabled) update_mptable boot quirk option is
disabled.

[ Impact: isolate the update_mptable feature from ACPI code more ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Len Brown <lenb@kernel.org>
LKML-Reference: <4A0DC832.5090200@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
index e6bf9d0..651c93b 100644
--- a/arch/x86/kernel/mpparse.c
+++ b/arch/x86/kernel/mpparse.c
@@ -957,7 +957,7 @@
 	return 0;
 }
 
-static int __initdata enable_update_mptable;
+int enable_update_mptable;
 
 static int __init update_mptable_setup(char *str)
 {