genirq/chip: Prepare for code reduction

The interrupt flow handlers have similar patterns to decide whether to
handle an interrupt or not.

Provide common helper functions to allow removal of duplicated code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250429065420.682547546@linutronix.de