mfd: Use request_threaded_irq for twl4030-irq instead of irq_set_chained_handler

irq_set_chained_handler sets 'desc->handle_irq'.
However this irq is called by handle_nested_irq from handle_twl4030_pih,
and that uses action->thread_fn.

So the handled set with irq_set_chained_handler is never called.

So change to use request_threaded_irq instead - that sets the correct field.

Tested on GTA04 Phoenux.

Signed-off-by: NeilBrown <neilb@suse.de>
Tested-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>