native_posix: Add logger configuration backend
native_posix: Add logger configuration backend

Enable native logger backend for native_posix board in defconfig.
Set also logger configuration options suitable for native_posix
backend.

Signed-off-by: Alberto Escolar Piedras <52be3174920ed06cbdfbcf9622a1a6c68e942617@oticon.com>
Signed-off-by: Andrei Emeltchenko <a6565233ddc88e4fb9c66c1d70743223493f2ed4@intel.com>

galak/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,finikorg/zephyr,Vudentz/zephyr,explora26/zephyr,punitvara/zephyr,nashif/zephyr,ldts/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,punitvara/zephyr,punitvara/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,kraj/zephyr,ldts/zephyr,kraj/zephyr,ldts/zephyr,Vudentz/zephyr,punitvara/zephyr,punitvara/zephyr,galak/zephyr,nashif/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,explora26/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,kraj/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr,galak/zephyr