thermal/drivers/samsung: Fix Wvoid-pointer-to-enum-cast warning

'soc' is an enum, thus cast of pointer on 64-bit compile test with W=1
causes:

  exynos_tmu.c:890:14: error: cast to smaller integer type 'enum soc_type' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230810091318.70261-1-krzysztof.kozlowski@linaro.org