isdn/gigaset: leave DLE mode before hanging up

Some firmware releases of Gigaset M105 do not accept AT+VLS=0 command
in DLE mode, so always leave DLE mode before sending the command.
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/gigaset/ev-layer.c

@@ -1693,6 +1693,11 @@ static void process_command_flags(struct cardstate *cs)
 	for (i = 0; i < cs->channels; ++i) {
 		bcs = cs->bcs + i;
 		if (bcs->at_state.pending_commands & PC_HUP) {
+			if (cs->dle) {
+				cs->curchannel = bcs->channel;
+				schedule_sequence(cs, &cs->at_state, SEQ_DLE0);
+				return;
+			}
 			bcs->at_state.pending_commands &= ~PC_HUP;
 			if (bcs->at_state.pending_commands & PC_CID) {
 				/* not yet dialing: PC_NOCID is sufficient */