ASoC: sst-bxt-da7219_max98357a: fix obsoleted initializer for array

Smatch reports below warnings:

    bxt_da7219_max98357a.c:352:9: warning: obsolete array initializer,
    use C99 syntax

An earlier commit cleaned up similar warnings, however, a recent
commit 43c02ede ("ASoC: Intel: Add DMIC channel constraint for
bxt machine") re-introduced the older initializer style. So fix
this warning to make the code consistent.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/boards/bxt_da7219_max98357a.c

@@ -348,7 +348,7 @@ static struct snd_soc_dai_link broxton_dais[] = {
 		.dynamic = 1,
 		.ops = &broxton_refcap_ops,
 	},
-	[BXT_DPCM_AUDIO_DMIC_CP]
+	[BXT_DPCM_AUDIO_DMIC_CP] =
 	{
 		.name = "Bxt Audio DMIC cap",
 		.stream_name = "dmiccap",