mfd: Remove bitrotted genirq comment from wm831x IRQ code

#include <linux/delay.h>

/*

 * Since generic IRQs don't currently support interrupt controllers on

 * interrupt driven buses we don't use genirq but instead provide an

 * interface that looks very much like the standard ones.  This leads

 * to some bodges, including storing interrupt handler information in

 * the static irq_data table we use to look up the data for individual

 * interrupts, but hopefully won't last too long.

 */

struct wm831x_irq_data {

	int primary;

	int reg;