regulator: lp872x: Fix Wvoid-pointer-to-enum-cast warning

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

  lp872x.c:867:5: error: cast to smaller integer type 'enum lp872x_regulator_id' from 'void *' [-Werror,-Wvoid-pointer-to-enum-cast]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230810111914.204847-3-krzysztof.kozlowski@linaro.org


Signed-off-by: Mark Brown <broonie@kernel.org>