x25_asy.c: silence compiler warning

Commit 11b0cc3a ("x25_asy: Fix ref count
rule violation") introduced the warning

  drivers/net/wan/x25_asy.c: In function `x25_asy_open_tty':
  drivers/net/wan/x25_asy.c:557: warning: unused variable `ld'
Signed-off-by: NS.Çağlar Onur <caglar@pardus.org.tr>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/net/wan/x25_asy.c

@@ -554,7 +554,6 @@ static void x25_asy_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 static int x25_asy_open_tty(struct tty_struct *tty)
 {
 	struct x25_asy *sl = (struct x25_asy *) tty->disc_data;
-	struct tty_ldisc *ld;
 	int err;
 
 	/* First make sure we're not already connected. */