Build osmo-bts and osmo-pcu from the tag instead of the commit, so we
don't need to update the commit. This is how it works in
meta-telephony.git already.
Fixes: 9a554791 ("Update Osmocom recipes to latest tags (release 202302)")
Change-Id: Id55552c25dc49fee6d6b48f2b5c50b008104ba60