mfd: wm8994: Fix Wvoid-pointer-to-enum-cast warning

mfd: wm8994: Fix Wvoid-pointer-to-enum-cast warning

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

  wm8994-core.c:631:19: error: cast to smaller integer type 'enum wm8994_type' from 'const void *' [-Werror,-Wvoid-pointer-to-enum-cast]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230810095849.123321-7-krzysztof.kozlowski@linaro.org
Signed-off-by: Lee Jones <lee@kernel.org>