RISC-V: add of_node_put()

use of_node_put() to release the refcount.
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/kernel/time.c

@@ -26,6 +26,7 @@ void __init time_init(void)
 	cpu = of_find_node_by_path("/cpus");
 	if (!cpu || of_property_read_u32(cpu, "timebase-frequency", &prop))
 		panic(KERN_WARNING "RISC-V system with no 'timebase-frequency' in DTS\n");
+	of_node_put(cpu);
 	riscv_timebase = prop;
 
 	lpj_fine = riscv_timebase / HZ;