MIPS: Loongson64: Add missing of_node_put() in ls2k_reset_init()

This node pointer is returned by of_find_compatible_node() with
refcount incremented in ls2k_reset_init(). Calling of_node_put()
to aovid the refcount leak.

Fixes: 7eb7819a ("MIPS: Loongson64: Add Loongson-2K1000 reset platform driver")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>