ASoC: Fix build without CONFIG_GPIOLIB

snd_soc_jack_gpio stuff is currently enabled for CONFIG_GPIOLIB
explicitly with ifdef, and this causes build errors on some drivers
such as:
  sound/soc/omap/rx51.c:220:33: error: array type has incomplete element type

Remove ifdef and provide dummy functions for CONFIG_GPIOLIB=n case
instead.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@linaro.org>