irq: Add irq_is_enabled external interrupt API

Add irq_is_enabled external interrupt API to find out if an
IRQ is enabled.

Change-id: I4e4fb6318f0c9da442926b34aa6773eb11e90efe
Signed-off-by: Vinayak Chettimada <vinayak.kariappa.chettimada@nordicsemi.no>
1 file changed