samples: flash_shell: Fix overwriting return value
samples: flash_shell: Fix overwriting return value

Value of ret has been overwritten by flash_write_protection_set
before it could be returned from do_write_unaligned, which could
lead to reporting success when error code should have been returned.

Fixes #27641, Coverity-CID: 212142
Fixes #27642, Coverity-CID: 212143

Signed-off-by: Dominik Ermel <1a1d45a9cc0c98a37f8d0a0d2dbe3cacc0b2344f@nordicsemi.no>

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