ASoC: Fix MAX98357A codec driver dependencies

The max98357a driver depends on GPIOLIB. This may cause the following
build failure.

sound/soc/codecs/max98357a.c: In function 'max98357a_daiops_trigger':
sound/soc/codecs/max98357a.c:30:3: error: implicit declaration of function 'gpiod_set_value'
sound/soc/codecs/max98357a.c: In function 'max98357a_codec_probe':
sound/soc/codecs/max98357a.c:55:2: error: implicit declaration of function 'devm_gpiod_get'
sound/soc/codecs/max98357a.c:61:2: error: implicit declaration of function 'gpiod_direction_output'

Seen with mips:allmodconfig as well as various randconfig builds.

Fixes: af5adf12 ("ASoC: max98357a: Add MAX98357A codec driver")
Cc: Kenneth Westfield <kwestfie@codeaurora.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Mark Brown <broonie@kernel.org>