ASoC: Intel: byt-rt5640: Add quirk for Dell Venue 8 Pro tablet

It was found with help of Jan-Michael Brummer <jan.brummer@tabos.org> that
Dell Venue 8 Pro tablet has a digital microphone connected to DMIC2
interface of the RT564x.

This patch adds a DAPM route to DMIC2 and a quirk using it for that tablet.
Signed-off-by: NJarkko Nikula <jarkko.nikula@linux.intel.com>
Reported-by: NJan-Michael Brummer <jan.brummer@tabos.org>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/intel/byt-rt5640.c

@@ -49,6 +49,10 @@ static const struct snd_soc_dapm_route byt_rt5640_intmic_dmic1_map[] = {
 	{"DMIC1", NULL, "Internal Mic"},
 };
 
+static const struct snd_soc_dapm_route byt_rt5640_intmic_dmic2_map[] = {
+	{"DMIC2", NULL, "Internal Mic"},
+};
+
 static const struct snd_soc_dapm_route byt_rt5640_intmic_in1_map[] = {
 	{"Internal Mic", NULL, "MICBIAS1"},
 	{"IN1P", NULL, "Internal Mic"},
@@ -56,6 +60,7 @@ static const struct snd_soc_dapm_route byt_rt5640_intmic_in1_map[] = {
 
 enum {
 	BYT_RT5640_DMIC1_MAP,
+	BYT_RT5640_DMIC2_MAP,
 	BYT_RT5640_IN1_MAP,
 };
 
@@ -111,6 +116,15 @@ static const struct dmi_system_id byt_rt5640_quirk_table[] = {
 		},
 		.driver_data = (unsigned long *)BYT_RT5640_IN1_MAP,
 	},
+	{
+		.callback = byt_rt5640_quirk_cb,
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "DellInc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Venue 8 Pro 5830"),
+		},
+		.driver_data = (unsigned long *)(BYT_RT5640_DMIC2_MAP |
+						 BYT_RT5640_DMIC_EN),
+	},
 	{}
 };
 
@@ -138,6 +152,10 @@ static int byt_rt5640_init(struct snd_soc_pcm_runtime *runtime)
 		custom_map = byt_rt5640_intmic_in1_map;
 		num_routes = ARRAY_SIZE(byt_rt5640_intmic_in1_map);
 		break;
+	case BYT_RT5640_DMIC2_MAP:
+		custom_map = byt_rt5640_intmic_dmic2_map;
+		num_routes = ARRAY_SIZE(byt_rt5640_intmic_dmic2_map);
+		break;
 	default:
 		custom_map = byt_rt5640_intmic_dmic1_map;
 		num_routes = ARRAY_SIZE(byt_rt5640_intmic_dmic1_map);