ASoC: wm8994: mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 402005
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wm8994.c

@@ -860,6 +860,7 @@ static void vmid_reference(struct snd_soc_codec *codec)
 		switch (wm8994->vmid_mode) {
 		default:
 			WARN_ON(NULL == "Invalid VMID mode");
+			/* fall through */
 		case WM8994_VMID_NORMAL:
 			/* Startup bias, VMID ramp & buffer */
 			snd_soc_update_bits(codec, WM8994_ANTIPOP_2,
@@ -2654,6 +2655,7 @@ static int wm8994_set_dai_fmt(struct snd_soc_dai *dai, unsigned int fmt)
 	case SND_SOC_DAIFMT_DSP_B:
 		aif1 |= WM8994_AIF1_LRCLK_INV;
 		lrclk |= WM8958_AIF1_LRCLK_INV;
+		/* fall through */
 	case SND_SOC_DAIFMT_DSP_A:
 		aif1 |= 0x18;
 		break;