x86, pic: Make use of legacy_pic abstraction

This patch replaces legacy PIC-related global variable and functions
with the new legacy_pic abstraction.

Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
LKML-Reference: <43F901BD926A4E43B106BF17856F07559FB80D04@orsmsx508.amr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/kernel/apic/nmi.c b/arch/x86/kernel/apic/nmi.c
index 0159a69..3817739 100644
--- a/arch/x86/kernel/apic/nmi.c
+++ b/arch/x86/kernel/apic/nmi.c
@@ -177,7 +177,7 @@
 error:
 	if (nmi_watchdog == NMI_IO_APIC) {
 		if (!timer_through_8259)
-			disable_8259A_irq(0);
+			legacy_pic->chip->mask(0);
 		on_each_cpu(__acpi_nmi_disable, NULL, 1);
 	}