mfd: mxs-lradc: Fix Wvoid-pointer-to-enum-cast warning

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

  mxs-lradc.c:145:15: error: cast to smaller integer type 'enum mxs_lradc_id' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230810095849.123321-9-krzysztof.kozlowski@linaro.org


Signed-off-by: Lee Jones <lee@kernel.org>