Revert "latona: wifi: set enabled_at_boot flag to true"

GPIO_WLAN_EN state depends on the bootloader and it appears that
certain bootloader versions are toggling them high on boot whereas
others are leaving them low. Few users have reported issues with
no wifi after boot probably because they have a bootloader that
behaves differently.

This reverts commit fad461edb13ec9ba10031960dab0deddb3905387.

Change-Id: I18b0debdb6139a5e768ad0707cc9ca604ec22aa8