Add u-boot and flashmap to manifest Needed to compile the sdk BUG=b/177367546 TEST=repo init, repo sync RELEASE_NOTE=None Change-Id: I34bdfaf8a83a3824074480211a74fcfa8c3a0cd4 Reviewed-on: https://cos-review.googlesource.com/c/cos/manifest/+/34461 Tested-by: Robert Kolchmeyer <rkolchmeyer@google.com> Reviewed-by: Dexter Rivera <riverade@google.com>