arm: zynq: Add missing irqchip.h to common.c

The patch: "ARM: use common irqchip_init for GIC init"
(sha1: 0529e315bbda5d502c93df2cfafba9bb337fbdf4)
should also add linux/irqchip.h header.

Error message:
arch/arm/mach-zynq/common.c:99:14: error: 'irqchip_init'
  undeclared here (not in a function)

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/mach-zynq/common.c

@@ -24,6 +24,7 @@
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/of.h>
+#include <linux/irqchip.h>
 
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>