ASoC: Intel: sof_es8336: simplify speaker gpio naming

ASoC: Intel: sof_es8336: simplify speaker gpio naming

In preparation for the support of an additional gpio for headphone
control, rename GPIOs to make explicit references to speakers and
gpio0 or gpio1.

No functionality change.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/3008c576ca45d5cc99ad4a18d1d30de45a0aff80.1649357263.git.mchehab@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>