mfd: twl6030-irq: Create struct twl6030_irq

Create "struct twl6030_irq" and place all local variables inside it.
Also allocate twl6030_irq structure dynamically during initialization.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Graeme Gregory <gg@slimlogic.co.uk>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>