Currently the enableIpServing->tetherInternal call stack may have a
tethering request alongside a redundant tethering type and requested
state. The redundant arguments were necessary since there may be cases
where the active request is null (e.g. back-to-back start/stop, which
removes the active request before the link layer event enables ip
serving).
This change gets rid of the redundant arguments and makes the call stack
take a non-null TetheringRequest. In case the active request is not
found, we will create a placeholder request with just the type and
connectivity scope (i.e. requested state). This should be equivalent to
the old code of sending a null request (since none of the other fields
in TetheringRequest are used), making this a no-op change.
Bug: 216524590
Test: covered by existing tests
Change-Id: I5ac83c74f5bc4aec2fe85daa9477740749d95c63
2b8a42d666