net: buf: Add a user_data's default and range for TCP2
net: buf: Add a user_data's default and range for TCP2

TCP2 uses the user_data area for linking the network buffers
in its windows.

Signed-off-by: Oleg Zhurakivskyy <cdb82bfa180f8df716a77d2c2557196a597a233c@intel.com>

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