devtool: finish: improve reporting for removed files

If a file is going to be effectively removed from the destination by
devtool finish, we should report that rather than just reporting that
we're removing files from the workspace. This is a little tricky because
the way we actually operate when finishing is to:
 (1) remove all original files (as recorded by devtool upgrade, if that
     was used)
 (2) as part of updating the recipe file, remove the files from next to
     the new recipe (i.e. in the workspace for an upgrade, real recipe
     otherwise) corresponding to commits not in the git tree
 (3) copy over remaining files from the workspace to the destination

To report the files removed with respect to what was originally there,
we need to swap steps 1 and 2 so we can see what no longer exists after
the deletion, and suppress the reporting currently done in step 2 -
however, we still want to report removal in step 2 for the non-upgrade
case, so the latter is conditional.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>