ASoC: Intel: boards: add 'static' qualifiers for max98390 routes

Sparse warnings:

sound/soc/intel/boards/sof_maxim_common.c:140:33: error: symbol
'max_98390_dapm_routes' was not declared. Should it be static?

sound/soc/intel/boards/sof_maxim_common.c:156:33: error: symbol
'max_98390_tt_dapm_routes' was not declared. Should it be static?

Fixes: f316c9d9ba ('ASoC: Intel: boards: add max98390 2/4 speakers support')
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20211207211700.115319-1-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/boards/sof_maxim_common.c

@@ -137,7 +137,7 @@ EXPORT_SYMBOL_NS(max_98373_set_codec_conf, SND_SOC_INTEL_SOF_MAXIM_COMMON);
 /*
  * Maxim MAX98390
  */
-const struct snd_soc_dapm_route max_98390_dapm_routes[] = {
+static const struct snd_soc_dapm_route max_98390_dapm_routes[] = {
 	/* speaker */
 	{ "Left Spk", NULL, "Left BE_OUT" },
 	{ "Right Spk", NULL, "Right BE_OUT" },
@@ -153,7 +153,7 @@ static const struct snd_soc_dapm_widget max_98390_tt_dapm_widgets[] = {
 	SND_SOC_DAPM_SPK("TR Spk", NULL),
 };
 
-const struct snd_soc_dapm_route max_98390_tt_dapm_routes[] = {
+static const struct snd_soc_dapm_route max_98390_tt_dapm_routes[] = {
 	/* Tweeter speaker */
 	{ "TL Spk", NULL, "Tweeter Left BE_OUT" },
 	{ "TR Spk", NULL, "Tweeter Right BE_OUT" },