soc: qcom: apr: Add of_node_put() before return

Fix following coccicheck warning:

./drivers/soc/qcom/apr.c:485:1-23: WARNING: Function
for_each_child_of_node should have of_node_put() before return

Early exits from for_each_child_of_node should decrement the
node reference counter.

Fixes: 83473566 ("soc: qcom: apr: Add avs/audio tracking functionality")
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211014083017.19714-1-wanjiabing@vivo.com