parsers: use common library code to rename sigrok channels

Drop an open coded g_free() and g_strdup() sequence which accesses
internal details of a sigrok channel. Use the sr_dev_channel_name_set()
library routine instead.

parsers.c

@@ -139,8 +139,7 @@ GSList *parse_channelstring(struct sr_dev_inst *sdi, const char *channelstring)
 			}
 			if (names[1]) {
 				/* Rename channel. */
-				g_free(ch->name);
-				ch->name = g_strdup(names[1]);
+				sr_dev_channel_name_set(ch, names[1]);
 			}
 			channellist = g_slist_append(channellist, ch);