ASoC: soc-generic-dmaengine-pcm: Fix sparse warnings

Currently the following sparse warnings are observed:

sound/soc/soc-generic-dmaengine-pcm.c:185:34: warning: restricted snd_pcm_format_t degrades to integer
sound/soc/soc-generic-dmaengine-pcm.c:186:66: warning: incorrect type in argument 1 (different base types)
sound/soc/soc-generic-dmaengine-pcm.c:186:66: expected restricted snd_pcm_format_t [usertype] format
sound/soc/soc-generic-dmaengine-pcm.c:186:66: got int [signed] [assigned] i

Fix it by changing the loop variable to be of 'snd_pcm_format_t'.

Also introduce a SNDRV_PCM_FORMAT_FIRST label, which corresponds to the
first member (index 0) of the snd_pcm_format_t formats.

Signed-off-by: Fabio Estevam <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

include/uapi/sound/asound.h

···
 #define	SNDRV_PCM_FORMAT_DSD_U16_BE	((__force snd_pcm_format_t) 51) /* DSD, 2-byte samples DSD (x16), big endian */
 #define	SNDRV_PCM_FORMAT_DSD_U32_BE	((__force snd_pcm_format_t) 52) /* DSD, 4-byte samples DSD (x32), big endian */
 #define	SNDRV_PCM_FORMAT_LAST		SNDRV_PCM_FORMAT_DSD_U32_BE
+#define	SNDRV_PCM_FORMAT_FIRST		SNDRV_PCM_FORMAT_S8
 
 #ifdef SNDRV_LITTLE_ENDIAN
 #define	SNDRV_PCM_FORMAT_S16		SNDRV_PCM_FORMAT_S16_LE

sound/soc/soc-generic-dmaengine-pcm.c

···
 	u32 addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
 			  BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
 			  BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
-	int i, ret;
+	snd_pcm_format_t i;
+	int ret;
 
 	if (pcm->config && pcm->config->pcm_hardware)
 		return snd_soc_set_runtime_hwparams(substream,
···
 		 * default assumption is that it supports 1, 2 and 4 bytes
 		 * widths.
 		 */
-		for (i = 0; i <= SNDRV_PCM_FORMAT_LAST; i++) {
+		for (i = SNDRV_PCM_FORMAT_FIRST; i <= SNDRV_PCM_FORMAT_LAST; i++) {
 			int bits = snd_pcm_format_physical_width(i);
 
 			/*