ASoC: Intel: sof_es8336: make gpio optional

ASoC: Intel: sof_es8336: make gpio optional

Do not fail if the GPIO used for speakers is not present, at least the
headphone, headset and internal mics should work.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20220308192610.392950-12-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>