staging: fieldbus: anybus-s: rename bus id field to avoid confusion

Rename the anybus-s bus id from fieldbus_type to anybus_id, to
avoid confusion with an identically named variable in the
fieldbus_dev framework.

Although this value is called fieldbus_type in the anybus-s docs,
it acts like a bus id, so the name change is appropriate.

Signed-off-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>