fs/nvs: prevent use after clear without init
fs/nvs: prevent use after clear without init

Unset ready flag in nvs instance on clear.

Signed-off-by: Ioannis Papamanoglou <c66d481368c8f74cb8077e1c8ca80d02bf73f8e0@zonneplan.nl>

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