mfd: Remove davinci voicecodec driver

The ASoC davinci voicecodec support is no longer used after
the removal of the dm3xx SoC platform, so the MFD driver is never
selected.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20221019152947.3857217-11-arnd@kernel.org