ARM: dts: exynos: correct TMU phandle in Odroid XU3 family

ARM: dts: exynos: correct TMU phandle in Odroid XU3 family

TMU node uses 0 as thermal-sensor-cells, thus thermal zone referencing
it must not have an argument to phandle.  This was not critical before,
but since rework of thermal Devicetree initialization in the
commit 3fd6d6e2b4e8 ("thermal/of: Rework the thermal device tree
initialization"), this leads to errors registering thermal zones other
than first one:

  thermal_sys: cpu0-thermal: Failed to read thermal-sensors cells: -2
  thermal_sys: Failed to find thermal zone for tmu id=0
  exynos-tmu 10064000.tmu: Failed to register sensor: -2
  exynos-tmu: probe of 10064000.tmu failed with error -2

Fixes: f1722d7dd8b8 ("ARM: dts: Define default thermal-zones for exynos5422")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20230209105841.779596-6-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>