genirq: Introduce irq_chip_set_type_parent() helper

This helper is required for irq chips which do not implement a
irq_set_type callback and need to call down the irq domain hierarchy
for the actual trigger type change.

This helper is required to fix further wreckage caused by the
conversion of TI OMAP to hierarchical irq domains and therefor tagged
for stable.

[ tglx: Massaged changelog ]

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: <linux@arm.linux.org.uk>
Cc: <nsekhar@ti.com>
Cc: <jason@lakedaemon.net>
Cc: <balbi@ti.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: <tony@atomide.com>
Cc: <marc.zyngier@arm.com>
Cc: stable@vger.kernel.org # 4.1
Link: http://lkml.kernel.org/r/1439554830-19502-3-git-send-email-grygorii.strashko@ti.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>