kconfig: fix typo in compiler options
kconfig: fix typo in compiler options

This commit fix the misspelling of the word "diagnostics"

Signed-off-by: MORGER Patrick <4480c6f8bb994c72c2d568d88c5a38191e7882d5@leica-geosystems.com>

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