dt-bindings: thermal: tsens: add per-sensor cells for msm8974

The msm8974 platform uses two sets of calibration data, add a special
case to handle both of them.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>