Bluetooth: fix MGMT_EV_NEW_LONG_TERM_KEY event

This patch fixes how MGMT_EV_NEW_LONG_TERM_KEY event is build. Right now
val vield is filled with only 1 byte, instead of whole value. This bug
was introduced in
commit 1fc62c52 ("Bluetooth: Fix exposing full value of shortened LTKs")

Before that patch, if you paired with device using bluetoothd using simple
pairing, and then restarted bluetoothd, you would be able to re-connect,
but device would fail to establish encryption and would terminate
connection. After this patch connecting after bluetoothd restart works
fine.
Signed-off-by: Jakub Pawlowski <jpawlowski@google.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/mgmt.c

@@ -7820,7 +7820,7 @@ void mgmt_new_ltk(struct hci_dev *hdev, struct smp_ltk *key, bool persistent)
 	/* Make sure we copy only the significant bytes based on the
 	 * encryption key size, and set the rest of the value to zeroes.
 	 */
-	memcpy(ev.key.val, key->val, sizeof(key->enc_size));
+	memcpy(ev.key.val, key->val, key->enc_size);
 	memset(ev.key.val + key->enc_size, 0,
 	       sizeof(ev.key.val) - key->enc_size);