ASoC: ab8500-codec: remove platform data based probe

The ux500 platform hasn't used board files for a long time, and
nothing defines a ab8500_codec_platform_data, so we can just
remove the probing based on that and always use device tree
properties directly.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>