Bluetooth: L2CAP: Fix type confusion in l2cap_ecred_reconf_rsp()

Bluetooth: L2CAP: Fix type confusion in l2cap_ecred_reconf_rsp()

l2cap_ecred_reconf_rsp() casts the incoming data to struct
l2cap_ecred_conn_rsp (the ECRED *connection* response, 8 bytes with
result at offset 6) instead of struct l2cap_ecred_reconf_rsp (2 bytes
with result at offset 0).

This causes two problems:

 - The sizeof(*rsp) length check requires 8 bytes instead of the
   correct 2, so valid L2CAP_ECRED_RECONF_RSP packets are rejected
   with -EPROTO.

 - rsp->result reads from offset 6 instead of offset 0, returning
   wrong data when the packet is large enough to pass the check.

Fix by using the correct type.  Also pass the already byte-swapped
result variable to BT_DBG instead of the raw __le16 field.

Fixes: 15f02b910562 ("Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode")
Cc: stable@vger.kernel.org
Signed-off-by: Lukas Johannes Möller <research@johannes-moeller.dev>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>