x86, apic: Remove ioapic_disable_legacy()

The ioapic_disable_legacy() call is no longer needed for platforms do
not have legacy pic. the legacy pic abstraction has taken care it
automatically.

This patch also initialize irq-related static variables based on
information obtained from legacy_pic.

Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
LKML-Reference: <43F901BD926A4E43B106BF17856F0755A30A7660@orsmsx508.amr.corp.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/include/asm/io_apic.h

@@ -143,8 +143,6 @@ extern int noioapicreroute;
 /* 1 if the timer IRQ uses the '8259A Virtual Wire' mode */
 extern int timer_through_8259;
 
-extern void io_apic_disable_legacy(void);
-
 /*
  * If we use the IO-APIC for IRQ routing, disable automatic
  * assignment of PCI IRQ's.

arch/x86/kernel/apic/io_apic.c

@@ -143,11 +143,6 @@ static struct irq_cfg irq_cfgx[NR_IRQS_LEGACY];
 static struct irq_cfg irq_cfgx[NR_IRQS];
 #endif
 
-void __init io_apic_disable_legacy(void)
-{
-	nr_irqs_gsi = 0;
-}
-
 int __init arch_early_irq_init(void)
 {
 	struct irq_cfg *cfg;
@@ -156,6 +151,11 @@ int __init arch_early_irq_init(void)
 	int node;
 	int i;
 
+	if (!legacy_pic->nr_legacy_irqs) {
+		nr_irqs_gsi = 0;
+		io_apic_irqs = ~0UL;
+	}
+
 	cfg = irq_cfgx;
 	count = ARRAY_SIZE(irq_cfgx);
 	node= cpu_to_node(boot_cpu_id);