soc: qcom: smem_state: Add refcounting for the 'state->of_node'

In qcom_smem_state_register() and qcom_smem_state_release(), we
should better use of_node_get() and of_node_put() for the reference
creation and destruction of 'device_node'.

Fixes: 9460ae2f ("soc: qcom: Introduce common SMEM state machine code")
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220721135217.1301039-2-windhl@126.com