new_variant: update for volteer fitimage changes

- Add new variables to allow the fitimage binary and versions files
to be in different directories, but the default is that they're in
the same directory.
- Add new files that volteer's expects to find

TEST=run for each supported reference board.
Pay special attention to volteer and volteer2.

Change-Id: I0999871b97cccac8cd7506aa1dfe3852ba86cbc3
Tested-by: Paul Fagerburg <>
Reviewed-by: Nick Vaccaro <>
Commit-Queue: Paul Fagerburg <>
9 files changed