Currently amber have two subpackages: ambr and ambs
There is a cyclic dependency between these: ambr depends each
subpackage, and each subpackage depends on ambr.
This makes scripts/buildorder.py (used by build-all.sh) error out.
And there is also no point in this current package split, as all three
packages will always be installed together due to the cyclic dependency.
So let's remove the subpackage split.