mfd: ab8500: provide a irq_set_type() function

In the AB8500 IRQ mask and unmask functions, we rely on testing for
IRQ_TYPE_EDGE_RISING and IRQ_TYPE_EDGE_FALLING interrupts to
physically mask and unmask the correct interrupt lines. In order
for us to do that, the trigger needs to be set in the associated
flags. However, unless a irq_set_type() function pointer is passed
when registering the IRQ chip, the IRQ subsystem will refuse to do
it. For that reason, we're providing one.

Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/mfd/ab8500-core.c

@@ -407,6 +407,11 @@ static void ab8500_irq_unmask(struct irq_data *data)
 	}
 }
 
+static int ab8500_irq_set_type(struct irq_data *data, unsigned int type)
+{
+	return 0;
+}
+
 static struct irq_chip ab8500_irq_chip = {
 	.name			= "ab8500",
 	.irq_bus_lock		= ab8500_irq_lock,
@@ -414,6 +419,7 @@ static struct irq_chip ab8500_irq_chip = {
 	.irq_mask		= ab8500_irq_mask,
 	.irq_disable		= ab8500_irq_mask,
 	.irq_unmask		= ab8500_irq_unmask,
+	.irq_set_type		= ab8500_irq_set_type,
 };
 
 static int ab8500_handle_hierarchical_line(struct ab8500 *ab8500,