tegra-alt: adsp: ignore drain msg to audioserver

On drain trigger no special handling is required on
audioserver side. Change adds case to ignore drain
message to audioserver.

Bug 2117496

Change-Id: I575b895651ed21179c743a0aa0e5f63eea354a5a
Signed-off-by: dipeshg <dipeshg@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1812302
Reviewed-by: Uday Gupta <udayg@nvidia.com>
Reviewed-by: Hariharan Sivaraman <hariharans@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Nitin Pai <npai@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

sound/soc/tegra-alt/tegra210_adsp_alt.c

@@ -2090,6 +2090,9 @@ static uint32_t tegra210_adsp_hv_pcm_trigger(
 			return ret;
 		}
 		break;
+	 case SNDRV_PCM_TRIGGER_DRAIN:
+		/* do nothing */
+		break;
 	default:
 		pr_err("Unsupported state.");
 		return -EINVAL;