xen/spinlock: Fix check from greater than to be also be greater or equal to.

During review of git commit cb9c6f15
("xen/spinlock:  Check against default value of -1 for IRQ line.")
Stefano pointed out a bug in the patch. Unfortunatly due to vacation
timing the fix was not applied and this patch fixes it up.
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/spinlock.c

@@ -364,7 +364,7 @@ void __cpuinit xen_init_lock_cpu(int cpu)
 	int irq;
 	const char *name;
 
-	WARN(per_cpu(lock_kicker_irq, cpu) > 0, "spinlock on CPU%d exists on IRQ%d!\n",
+	WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
 	     cpu, per_cpu(lock_kicker_irq, cpu));
 
 	/*