x86/apic: Do not clear nr_irqs_gsi if no legacy irqs

nr_legacy_irqs is set in probe_nr_irqs_gsi, we should not clear
it after that. Otherwise, the result is that MSI irqs will be
allocated from the wrong range for the systems without legacy
PIC.
Signed-off-by: NJacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: NDirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/apic/io_apic.c

@@ -193,10 +193,8 @@ int __init arch_early_irq_init(void)
 	struct irq_cfg *cfg;
 	int count, node, i;
 
-	if (!legacy_pic->nr_legacy_irqs) {
-		nr_irqs_gsi = 0;
+	if (!legacy_pic->nr_legacy_irqs)
 		io_apic_irqs = ~0UL;
-	}
 
 	for (i = 0; i < nr_ioapics; i++) {
 		ioapics[i].saved_registers =