PM / devfreq: exynos-ppmu: remove unneeded of_node_put()

for_each_child_of_node() performs an of_node_put() on each iteration, so
putting an of_node_put() before a continue results in a double put.

Generated by: scripts/coccinelle/iterators/device_node_continue.cocci

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>