ASoC: intel: avs: refactor strncpy usage in topology

`strncpy` is deprecated for use on NUL-terminated destination strings
[1].

A suitable replacement is `strscpy` [2].

There are some hopes that someday the `strncpy` api could be ripped out
due to the vast number of suitable replacements (strscpy, strscpy_pad,
strtomem, strtomem_pad, strlcpy) [1].

[1]: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
[2]: manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html

Link: https://github.com/KSPP/linux/issues/90
Signed-off-by: Justin Stitt <[e-mail]>
Link: https://lore.kernel.org/r/20230725[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/intel/avs/topology.c

···
 		port = __ffs(mach->mach_params.i2s_link_mask);
 
 		snprintf(buf, len, route->source, port);
-		strncpy((char *)route->source, buf, len);
+		strscpy((char *)route->source, buf, len);
 		snprintf(buf, len, route->sink, port);
-		strncpy((char *)route->sink, buf, len);
+		strscpy((char *)route->sink, buf, len);
 		if (route->control) {
 			snprintf(buf, len, route->control, port);
-			strncpy((char *)route->control, buf, len);
+			strscpy((char *)route->control, buf, len);
 		}
 	}