The files listing the SIG and TC repos use a list under each group with
a dict containing the key 'repo' and then the repository name. Make the
board file format consistent so that tools parsing these files have
fewer formats to deal with.
Change-Id: I2466e02be772ff96e43f377c7431af880a4cea1d
Signed-off-by: Doug Hellmann <doug@doughellmann.com>