Bluetooth: Mesh: Shell: Fix cfgCli appkey arg conv
Bluetooth: Mesh: Shell: Fix cfgCli appkey arg conv

Rectifies incorrect conversion of appkey string in config client
appkey add command.

Signed-off-by: Anders Storrø <455451b3187a9d78ea3eb42969d914022fdb8211@nordicsemi.no>

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