Skip baremetal config when there is no baremetal.

We want to be able to use boot-stack for booting an all-in-one
non-baremetal configuration as well.

Nova needs a lot of extra components for baremetal, these bits will fail
without the baremetal configuration section.

Change-Id: I24c073c7eb53a6cab92af2c6c30801b9a686f074