For certain irq types, e.g. gpios, it's necessary to request resources
before starting up the irq.

This might fail so we cannot use the irq_startup() callback because we
might call the irq_set_type() callback before that which does not make
sense when the resource is not available. Calling irq_startup() before
irq_set_type() can lead to spurious interrupts which is not desired
either.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org 
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1403080857160.18573@ionos.tec.linutronix.deSigned-off-by: Thomas Gleixner <tglx@linutronix.de>