Both wasapi2 and wasapi plugins use WASAPI API. So "device.api=wasapi"
would make sense for the wasapi2 plugin as well. But people would be
confused by the identical "device.api=wasapi" property if intended
plugin is wasapi, not wasapi2. This change will make them distinguishable
by using "device.api" device property.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2024>