tty: fix comment typo in synclink_gt.c

Fix typo "looopback" to "loopback" in synclink_gt.c

Signed-off-by: Masanari Iida<standby24x7@gmail.com>
cc:Jiri Koshina<jkosina@suze.cz>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

drivers/tty/synclink_gt.c

@@ -3924,7 +3924,7 @@ static void tdma_reset(struct slgt_info *info)
  */
 static void enable_loopback(struct slgt_info *info)
 {
-	/* SCR (serial control) BIT2=looopback enable */
+	/* SCR (serial control) BIT2=loopback enable */
 	wr_reg16(info, SCR, (unsigned short)(rd_reg16(info, SCR) | BIT2));
 
 	if (info->params.mode != MGSL_MODE_ASYNC) {