of: unittest: Add a case to test if API of_irq_parse_raw() leaks refcount

To test if of_irq_parse_raw(), invoked by of_irq_parse_one(), will leak
refcount of interrupt combo node consisting of controller and nexus.

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20250209-of_irq_fix-v2-3-93e3a2659aa7@quicinc.com


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>