ASoC: amd: acp-es8336: use static variables

Sparse warnings:

sound/soc/amd/acp-es8336.c:36:15: error: symbol 'codec_dev' was not
declared. Should it be static?

sound/soc/amd/acp-es8336.c:37:18: error: symbol 'gpio_pa' was not
declared. Should it be static?

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220707214614.61081-1-pierre-louis.bossart@linux.intel.com


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