gpio: pxa: explicitly include mach/irqs.h

In preparation to make mach/irqs.h optional and remove from asm/irq.h,
directly include mach/irq.h to get MMP_GPIO_TO_IRQ and PXA_GPIO_TO_IRQ.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

drivers/gpio/gpio-pxa.c

@@ -22,6 +22,8 @@
 #include <linux/syscore_ops.h>
 #include <linux/slab.h>
 
+#include <mach/irqs.h>
+
 /*
  * We handle the GPIOs by banks, each bank covers up to 32 GPIOs with
  * one set of registers. The register offsets are organized below: