genirq: Provide irq_desc_has_action

If we have a reference to irq_desc already, there is no point to do
another lookup.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Link: http://lkml.kernel.org/r/20150802203609.638130301@linutronix.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>