ASoC: codecs: max98390: fix 'defined but not used' warning

ASoC: codecs: max98390: fix 'defined but not used' warning

Fix W=1 warning and removed unused table. In this case this a
duplicate of

static const struct of_device_id max98390_of_match[] = {
	{ .compatible = "maxim,max98390", },
	{}
};
MODULE_DEVICE_TABLE(of, max98390_of_match);

already used in the rest of the code.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200707190612.97799-13-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>