ARM: mvebu: fix compilation warning on Armada 370 (i.e. non-SMP)

The following appears during compilation for an Armada 370 target
because 'irq_controller_lock' is used only when CONFIG_SMP is
enabled:

 drivers/irqchip/irq-armada-370-xp.c:62:8: warning: 'irq_controller_lock' defined but not used [-Wunused-variable]

Fix that warning by moving declaration of 'irq_controller_lock'
inside existing #ifdef.
Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-armada-370-xp.c

@@ -59,8 +59,6 @@
 #define PCI_MSI_DOORBELL_END                    (32)
 #define PCI_MSI_DOORBELL_MASK                   0xFFFF0000
 
-static DEFINE_RAW_SPINLOCK(irq_controller_lock);
-
 static void __iomem *per_cpu_int_base;
 static void __iomem *main_int_base;
 static struct irq_domain *armada_370_xp_mpic_domain;
@@ -239,6 +237,8 @@ static inline int armada_370_xp_msi_init(struct device_node *node,
 #endif
 
 #ifdef CONFIG_SMP
+static DEFINE_RAW_SPINLOCK(irq_controller_lock);
+
 static int armada_xp_set_affinity(struct irq_data *d,
 				  const struct cpumask *mask_val, bool force)
 {