Convert vendor specific **_WIFI_BUILD_ONLY_MODE symbol as global
in order to provide common build flag to enable CI with no blobs.
Signed-off-by: Sylvio Alves <sylvio.alves@espressif.com>
Following the naming convention add an underscore and update path in the
maintainers file too.
Signed-off-by: Chaitanya Tata <Chaitanya.Tata@nordicsemi.no>