irqchip/gic/realview: Fix refcount leak in realview_gic_of_init

In the Linux kernel, the following vulnerability has been resolved: irqchip/gic/realview: Fix refcount leak in realview_gic_of_init of_find_matching_node_and_match() returns a node pointer with refcount incremented, we should use of_node_put() on it when not need anymore. Add missing of_node_put() to avoid refcount leak.