ARM: ux500: Fix build error relating to IRQCHIP_SKIP_SET_WAKE

This patch fixes the build error below:

arch/arm/mach-ux500/cpu.c: In function ‘ux500_init_irq’:
arch/arm/mach-ux500/cpu.c:55:2: error: invalid use of undefined type ‘struct irq_chip’
arch/arm/mach-ux500/cpu.c:55:24: error: ‘IRQCHIP_SKIP_SET_WAKE’ undeclared (first use in this function)
arch/arm/mach-ux500/cpu.c:55:24: note: each undeclared identifier is reported only once for each function it appears in
arch/arm/mach-ux500/cpu.c:55:48: error: ‘IRQCHIP_MASK_ON_SUSPEND’ undeclared (first use in this function)

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

arch/arm/mach-ux500/cpu.c

@@ -16,6 +16,7 @@
 #include <linux/stat.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
+#include <linux/irq.h>
 #include <linux/platform_data/clk-ux500.h>
 
 #include <asm/hardware/gic.h>