net: lwm2m: Remove duplicated logs during bootstrap
net: lwm2m: Remove duplicated logs during bootstrap

Remove the `sm_bootstrap_reg_done` function, which produced duplicated
logs. The bootstrap registration done event is already logged on state
transition. Additionally, in case bootstrap procedure took longer time,
the duplicated log message was printed on each `lwm2m_rd_client_service`
call (500 miliseconds by default).

Signed-off-by: Robert Lubos <9d28997c6894a2d0321a7bb399169af7ce99b64e@nordicsemi.no>

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