ASoC: Intel: avs: Silence false-positive memcpy() warnings

Commit df8fc4e9 ("kbuild: Enable -fstrict-flex-arrays=3") enforced
strict flex array declarations. This generates false-positive in form of:
"memcpy: detected field-spanning write". Avoid it by utilizing the
DECLARE_FLEX_ARRAY() macro.
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://msgid.link/r/20240405090929.1184068-4-cezary.rojewski@intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/avs/messages.h

@@ -752,9 +752,9 @@ struct avs_copier_gtw_cfg {
 	union avs_connector_node_id node_id;
 	u32 dma_buffer_size;
 	u32 config_length;
-	struct {
+	union {
 		union avs_gtw_attributes attrs;
-		u32 blob[];
+		DECLARE_FLEX_ARRAY(u32, blob);
 	} config;
 } __packed;
 

sound/soc/intel/avs/path.c

@@ -254,7 +254,7 @@ static int avs_copier_create(struct avs_dev *adev, struct avs_path_module *mod)
 	/* config_length in DWORDs */
 	cfg->gtw_cfg.config_length = DIV_ROUND_UP(data_size, 4);
 	if (data)
-		memcpy(&cfg->gtw_cfg.config, data, data_size);
+		memcpy(&cfg->gtw_cfg.config.blob, data, data_size);
 
 	mod->gtw_attrs = cfg->gtw_cfg.config.attrs;