thermal/drivers/imx_sc: Add missing of_node_put for loop iteration

Early exits from for_each_available_child_of_node() should decrement the
node reference counter.  Reported by Coccinelle:

  drivers/thermal/imx_sc_thermal.c:93:1-33: WARNING:
    Function "for_each_available_child_of_node" should have of_node_put() before return around line 97.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Jacky Bai <ping.bai@nxp.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210614192230.19248-1-krzysztof.kozlowski@canonical.com