isicom: isicom kref leak fix

The isicom driver leaks a kref on the shutdown path. Drop the additional
kref we took

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index 24aa6e8..a59eac5 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -925,6 +925,7 @@
 		if (!card->count)
 			isicom_shutdown_board(card);
 	}
+	tty_kref_put(tty);
 }
 
 static void isicom_flush_buffer(struct tty_struct *tty)