editorconfig: Set insert_final_newline true
editorconfig: Set insert_final_newline true

This is what checkpatch.pl expects, and GitHub's file viewer flags a
missing trailing newline too.

Note that this is different from a blank line at the end of the file. It
just says whether the last line must end in a newline.

Signed-off-by: Ulf Magnusson <01743f1c1deb1fe75271d62edb65757d98ac0bcb@nordicsemi.no>

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