ipx: Remove spurious NULL checking in ipx_ioctl().

We already unconditionally dereference 'sk' via lock_sock(sk) earlier
in this function, and our caller (sock_do_ioctl()) makes takes similar
liberties.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipx/af_ipx.c

@@ -1901,9 +1901,7 @@ static int ipx_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 			      (const unsigned short __user *)argp);
 		break;
 	case SIOCGSTAMP:
-		rc = -EINVAL;
-		if (sk)
-			rc = sock_get_timestamp(sk, argp);
+		rc = sock_get_timestamp(sk, argp);
 		break;
 	case SIOCGIFDSTADDR:
 	case SIOCSIFDSTADDR: