isdn/gigaset: improve error handling when leaving DLE mode

Avoid cascading warnings when leaving DLE mode fails by clearing
the DLE flag before entering recovery.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/gigaset/ev-layer.c b/drivers/isdn/gigaset/ev-layer.c
index 7459b12..dcae14a 100644
--- a/drivers/isdn/gigaset/ev-layer.c
+++ b/drivers/isdn/gigaset/ev-layer.c
@@ -1243,7 +1243,8 @@
 		break;
 	case ACT_FAILDLE0:
 		cs->cur_at_seq = SEQ_NONE;
-		dev_warn(cs->dev, "Could not leave DLE mode.\n");
+		dev_warn(cs->dev, "Error leaving DLE mode.\n");
+		cs->dle = 0;
 		at_state2 = &cs->bcs[cs->curchannel].at_state;
 		disconnect(&at_state2);
 		schedule_init(cs, MS_RECOVER);