mfd: ab8500-core: Add Interrupt support for ab8540

ITSource/ITLatch 7, 8, 9 and 10 don't exist on AB8540. This patch
replaces them with '-1' in the interrupt list, and handles the '-1'
in the code accordingly.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>

include/linux/mfd/abx500/ab8500.h

@@ -362,6 +362,7 @@ struct ab8500 {
 	u8 *oldmask;
 	int mask_size;
 	const int *irq_reg_offset;
+	int it_latchhier_num;
 };
 
 struct regulator_reg_init;