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

To test if of_irq_parse_one(@int_gen_dev, i, ...) will leak refcount of
@i_th_phandle.

int_gen_dev {
	...
	interrupts-extended = ..., <&i_th_phandle ...>, ...;
	...
};

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20250209-of_irq_fix-v2-1-93e3a2659aa7@quicinc.com


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