Bluetooth: L2CAP: Truncate RX MTU if segmentation is not supported
Bluetooth: L2CAP: Truncate RX MTU if segmentation is not supported

If hannel don't have alloc_buf and the RX MTU is configured to require
segmentation this warn the user and truncate the RX MTU.

Signed-off-by: Luiz Augusto von Dentz <8530c5ea66a1bdbc08f98bfcf183c8be901b5990@intel.com>

galak/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,nashif/zephyr