mfd: Simulate active high IRQs with wm831x

In order to ease system integration provide a simulation of active high
IRQs on the GPIOs by polling the GPIO status when an IRQ is generated.

This isn't ideal on several fronts and will miss initially active IRQs in
the current implementation but it should work well for most cases.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

include/linux/mfd/wm831x/core.h

@@ -385,6 +385,7 @@ struct wm831x {
 
 	/* Used by the interrupt controller code to post writes */
 	int gpio_update[WM831X_NUM_GPIO_REGS];
+	bool gpio_level[WM831X_NUM_GPIO_REGS];
 
 	struct mutex auxadc_lock;
 	struct list_head auxadc_pending;