This reverts commit 6ee2995214 and
e85c2a6f03.
I missed that if you pip install and then run dib-lint, it's not going
to pick up the .yamllint file shipped here. Thus it gives spurious
errors.
The reason for this was simply better duplicate key detection in yaml
files, which caused us problems with the kernel installs. However, at
this point it seems just the old "does it load" test from pyyaml will
be enough.
Change-Id: I87a9fc9bb119cfeffad48fc0fa0df31f0181825d
0c94eef7be