net: l2: wifi: Fix Wi-Fi mode get command bug

The mode command operation has to be set to WIFI_MGMT_GET when the
option -g is provided. It was mistakenly set to true. Correcting the
same

This PR fixes #63424 and sets the proper value for the get command

Signed-off-by: Vivekananda Uppunda <vivekananda.uppunda@nordicsemi.no>