irqchip: Fix refcount leak in platform_irqchip_probe

of_irq_find_parent() returns a node pointer with refcount incremented,
We should use of_node_put() on it when not needed anymore.
Add missing of_node_put() to avoid refcount leak.

Fixes: f8410e62 ("irqchip: Add IRQCHIP_PLATFORM_DRIVER_BEGIN/END and IRQCHIP_MATCH helper macros")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230102121318.3990586-1-linmq006@gmail.com