mfd: Add support for twl6030 irq framework

This patch adds support for phoenix interrupt framework. New iInterrupt
status register A, B, C are introduced in Phoenix and are cleared on write.
Due to the differences in interrupt handling with respect to TWL4030,
twl6030-irq.c is created for TWL6030 PMIC

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Balaji T K <balajitk@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>