nvs: fix overwriting with truncated data
nvs: fix overwriting with truncated data

When overwriting an NVS item with data that was a truncated version of
the existing data, the "is this already saved" logic was ignoring the
differing lengths and not saving the new item because the data matched.

Fixes #19250

Signed-off-by: Justin Brzozoski <75be534442ec8559bffa39d9792e8c7c519bd7ec@signal-fire.com>

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