irqchip/realtek-rtl: Fix refcount leak in map_interrupts

In the Linux kernel, the following vulnerability has been resolved: irqchip/realtek-rtl: Fix refcount leak in map_interrupts of_find_node_by_phandle() returns a node pointer with refcount incremented, we should use of_node_put() on it when not need anymore. This function doesn't call of_node_put() in error path. Call of_node_put() directly after of_property_read_u32() to cover both normal path and error path.