Bluetooth: Classic: L2CAP: Fix seg_recv cannot work issue

When the L2CAP channel connection is in none basic mode, the
`seg_recv` cannot work properly if the configuration
`CONFIG_BT_L2CAP_SEG_RECV` is enabled. And the L2CAP channel
connection will be broken incorrectly.

Check whether the received data len exceeds the SDU length if the
`SAR` is `BT_L2CAP_CONTROL_SAR_END` or `BT_L2CAP_CONTROL_SAR_CONTI`.

And check whether the SDU length is valid if the `SAR` is
`BT_L2CAP_CONTROL_SAR_UNSEG` or `BT_L2CAP_CONTROL_SAR_START`.

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