hwspinlock: qcom_hwspinlock: add missing of_node_put after calling of_parse_phandle

of_node_put needs to be called when the device node which is got
from of_parse_phandle has finished using.

Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arm-msm@vger.kernel.org
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>