ASoC: max98373-sdw: add missing memory allocation check

We forgot to test that devm_kcalloc doesn't return NULL.

Fixes: 349dd239 ('ASoC: max98373: don't access volatile registers in bias level off')
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Bard Liao <bard.liao@intel.com>
Link: https://lore.kernel.org/r/20210607222239.582139-2-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/max98373-sdw.c

@@ -786,6 +786,8 @@ static int max98373_init(struct sdw_slave *slave, struct regmap *regmap)
 	max98373->cache = devm_kcalloc(dev, max98373->cache_num,
 				       sizeof(*max98373->cache),
 				       GFP_KERNEL);
+	if (!max98373->cache)
+		return -ENOMEM;
 
 	for (i = 0; i < max98373->cache_num; i++)
 		max98373->cache[i].reg = max98373_sdw_cache_reg[i];