wimax: i2400: fix memory leak

BugLink: https://bugs.launchpad.net/bugs/1860681

commit 2507e6ab upstream.

In i2400m_op_rfkill_sw_toggle cmd buffer should be released along with
skb response.
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/net/wimax/i2400m/op-rfkill.c

@@ -142,6 +142,7 @@ int i2400m_op_rfkill_sw_toggle(struct wimax_dev *wimax_dev,
 			"%d\n", result);
 	result = 0;
 error_cmd:
+	kfree(cmd);
 	kfree_skb(ack_skb);
 error_msg_to_dev:
 error_alloc: