arch: mips: generic: Add missing of_node_put() in board-ranchu.c

In ranchu_measure_hpt_freq(), of_find_compatible_node() will return
a node pointer with refcount incremented. We should use of_put_node()
when it is not used anymore.
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/generic/board-ranchu.c

@@ -44,6 +44,7 @@ static __init unsigned int ranchu_measure_hpt_freq(void)
 		      __func__);
 
 	rtc_base = of_iomap(np, 0);
+	of_node_put(np);
 	if (!rtc_base)
 		panic("%s(): Failed to ioremap Goldfish RTC base!", __func__);