DHCPv4Client: create UdpPacket unchecked

bug fix

Author: astro

src/dhcp/clientv4.rs

@@ -413,9 +413,9 @@ fn send_packet<DeviceT: for<'d> Device<'d>>(iface: &mut Interface<DeviceT>, raw_
         ipv4_repr.emit(&mut ipv4_packet, &checksum_caps);
     }
     {
-        let mut udp_packet = UdpPacket::new_checked(
+        let mut udp_packet = UdpPacket::new_unchecked(
             &mut packet[ipv4_repr.buffer_len()..]
-        )?;
+        );
         udp_repr.emit(&mut udp_packet,
                       &src_addr.into(), &dst_addr.into(),
                       checksum_caps);