x86: calibrate delay with irqs enabled

We do it to make it close to x86_64. The later needs it,
otherwise the nmi watchdog can get into the scene and kill us
with a hammer.

Enabling irqs here used to trigger a bug in i386. This is because
time irq handling relies upon structures that are only initialized
after smp initcalls (More precisely, it will find
per_cpu(hrtimer_bases, cpu)->cb_pending list not initialized and crash)
Signed-off-by: NGlauber Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/smpboot_32.c

@@ -167,7 +167,9 @@ static void __cpuinit smp_callin(void)
 	/*
 	 * Get our bogomips.
 	 */
+	local_irq_enable();
 	calibrate_delay();
+	local_irq_disable();
 	Dprintk("Stack at about %p\n",&cpuid);
 
 	/*