ALSA: hda: intel-nhlt: Correct the handling of fmt_config flexible array

The struct nhlt_format's fmt_config is a flexible array, it must not be
used as normal array.
When moving to the next nhlt_fmt_cfg we need to take into account the data
behind the ->config.caps (indicated by ->config.size).

Fixes: a864e8f1 ("ALSA: hda: intel-nhlt: verify config type")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Jaska Uimonen <jaska.uimonen@linux.intel.com>
Link: https://lore.kernel.org/r/20220823122405.18464-1-peter.ujfalusi@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/hda/intel-nhlt.c

@@ -55,16 +55,22 @@ 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;
+
 			dev_dbg(dev, "found %d format definitions\n",
 				fmt_configs->fmt_count);
 
 			for (i = 0; i < fmt_configs->fmt_count; i++) {
 				struct wav_fmt_ext *fmt_ext;
 
-				fmt_ext = &fmt_configs->fmt_config[i].fmt_ext;
+				fmt_ext = &fmt_cfg->fmt_ext;
 
 				if (fmt_ext->fmt.channels > max_ch)
 					max_ch = fmt_ext->fmt.channels;
+
+				/* Move to the next nhlt_fmt_cfg */
+				fmt_cfg = (struct nhlt_fmt_cfg *)(fmt_cfg->config.caps +
+								  fmt_cfg->config.size);
 			}
 			dev_dbg(dev, "max channels found %d\n", max_ch);
 		} else {