Bluetooth: Classic: L2CAP: Support `L2CAP_COMMAND_REJECT_RSP`

In current implementation, when receiving the L2CAP frame
`L2CAP_COMMAND_REJECT_RSP` if the L2CAP is working as client role, the
L2CAP frame `L2CAP_COMMAND_REJECT_RSP` will be sent by the L2CAP
client incorrectly.

When the command response `L2CAP_COMMAND_REJECT_RSP` is received, find
the channel of the command request according to the received `ident`.
If the channel is found, try to disconnect the channel. If fail to
disconnect the channel, remove and delete the channel.

Signed-off-by: Lyle Zhu <lyle.zhu@nxp.com>