x86: convert nmi_lock to atomic_spinlock

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/apic/nmi.c

@@ -416,12 +416,12 @@ nmi_watchdog_tick(struct pt_regs *regs, unsigned reason)
 
 	/* We can be called before check_nmi_watchdog, hence NULL check. */
 	if (backtrace_mask != NULL && cpumask_test_cpu(cpu, backtrace_mask)) {
-		static DEFINE_SPINLOCK(lock);	/* Serialise the printks */
+		static DEFINE_ATOMIC_SPINLOCK(lock);	/* Serialise the printks */
 
-		spin_lock(&lock);
+		atomic_spin_lock(&lock);
 		printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
 		dump_stack();
-		spin_unlock(&lock);
+		atomic_spin_unlock(&lock);
 		cpumask_clear_cpu(cpu, backtrace_mask);
 	}