ASoC: simple-amplifier: Remove spurious gpiolib select

The usage of GPIOs is optional in the code so don't force on gpiolib when
building it, avoiding warnings in randconfigs.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220202192333.3655269-4-broonie@kernel.org


Signed-off-by: Mark Brown <broonie@kernel.org>