samples: lwm2m: enables LwM2M shell commands
samples: lwm2m: enables LwM2M shell commands

Makes LwM2M SEND operation possible.

Signed-off-by: Veijo Pesonen <cb89a3750227d52d34160f03c031368aef19d3be@nordicsemi.no>

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