Bluetooth: L2CAP: Fix result of L2CAP_ECRED_CONN_RSP when MTU is too short

Bluetooth: L2CAP: Fix result of L2CAP_ECRED_CONN_RSP when MTU is too short

[ Upstream commit c28d2bff70444a85b3b86aaf241ece9408c7858c ]

Test L2CAP/ECFC/BV-26-C expect the response to L2CAP_ECRED_CONN_REQ with
and MTU value < L2CAP_ECRED_MIN_MTU (64) to be L2CAP_CR_LE_INVALID_PARAMS
rather than L2CAP_CR_LE_UNACCEPT_PARAMS.

Also fix not including the correct number of CIDs in the response since
the spec requires all CIDs being rejected to be included in the
response.

Link: https://github.com/bluez/bluez/issues/1868
Fixes: 15f02b910562 ("Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>