TWL6030: IRQ: Prevent interrup loss while dispatching TWL interrupts

When TWL interrupt occurs the interrupt register is read, then all pending
interrupts are dispatched and finally the interrupt status register is cleared.
Any interrupt ocurred during the dispatching will be never registered, because
the register will be cleared witout re-reading the status register.
Moving the interrupt status register clear code immediately after the register
read, prior to dispatch the interrupts, thus allowing any new event from TWL to
fire new interrupt.