ALSA: intel-nhlt: Change struct nhlt_fmt.fmt_config struct array to u8

The struct nhlt_fmt_cfg is a flexible array, because:
struct nhlt_fmt {
	...
	struct nhlt_fmt_cfg fmt_config[] { <- This
		...
		struct nhlt_specific_cfg {
			...
			u8 caps[]; <- Because of this
		};
	};
};

Strangely sparse did not complain about this, but it was misused by
drivers, treating it as a normal array and not a flexible one.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>

Author: ujfalusi

include/sound/intel-nhlt.h

@@ -58,7 +58,7 @@ struct nhlt_fmt_cfg {
 
 struct nhlt_fmt {
 	u8 fmt_count;
-	struct nhlt_fmt_cfg fmt_config[];
+	u8 fmt_config[];  /* flexible array of 'struct nhlt_fmt_cfg' */
 } __packed;
 
 struct nhlt_endpoint {

sound/hda/intel-nhlt.c

@@ -56,11 +56,12 @@ int intel_nhlt_get_dmic_geo(struct device *dev, struct nhlt_acpi_table *nhlt)
 
 		/* find max number of channels based on format_configuration */
 		if (fmt_configs->fmt_count) {
-			struct nhlt_fmt_cfg *fmt_cfg = fmt_configs->fmt_config;
+			struct nhlt_fmt_cfg *fmt_cfg;
 
 			dev_dbg(dev, "found %d format definitions\n",
 				fmt_configs->fmt_count);
 
+			fmt_cfg = (struct nhlt_fmt_cfg *)fmt_configs->fmt_config;
 			for (i = 0; i < fmt_configs->fmt_count; i++) {
 				struct wav_fmt_ext *fmt_ext;
 
@@ -189,7 +190,7 @@ int intel_nhlt_ssp_mclk_mask(struct nhlt_acpi_table *nhlt, int ssp_num)
 		    epnt->virtual_bus_id == ssp_num) {
 
 			fmt = (struct nhlt_fmt *)(epnt->config.caps + epnt->config.size);
-			cfg = fmt->fmt_config;
+			cfg = (struct nhlt_fmt_cfg *)fmt->fmt_config;
 
 			/*
 			 * In theory all formats should use the same MCLK but it doesn't hurt to
@@ -241,7 +242,7 @@ static struct nhlt_specific_cfg *
 nhlt_get_specific_cfg(struct device *dev, struct nhlt_fmt *fmt, u8 num_ch,
 		      u32 rate, u8 vbps, u8 bps, bool ignore_vbps)
 {
-	struct nhlt_fmt_cfg *cfg = fmt->fmt_config;
+	struct nhlt_fmt_cfg *cfg = (struct nhlt_fmt_cfg *)fmt->fmt_config;
 	struct wav_fmt *wfmt;
 	u16 _bps, _vbps;
 	int i;