devtool: upgrade: fix not committing deleted files with older git versions

devtool: upgrade: fix not committing deleted files with older git versions

With versions of git older than 2.0, "git add" on a deleted file (i.e.
in this case a file that was removed between versions) will not add the
delete to be committed by default, with the result that the rebase of
patches on top of the new branch will fail. We need to use the -A
option in order to force that for older git versions.

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