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>

external_full.xml

diff --git a/external_full.xml b/external_full.xml
index 408d06e..44b64f5 100644
--- a/external_full.xml
+++ b/external_full.xml
@@ -63,6 +63,12 @@
   <project path="infra_virtualenv"
            name="mirrors/cros/chromiumos/infra_virtualenv"
            revision="bfae4bfc108dd981bf3887b45cee10395253fe1d" />
+  <project path="src/third_party/u-boot/files"
+           name="mirrors/cros/chromiumos/third_party/u-boot"
+           revision="bc1199918e73f3f810b2eeb5dc38e71a5914772a" />
+  <project path="src/third_party/flashmap"
+           name="mirrors/cros/chromiumos/third_party/flashmap"
+           revision="2f7b2e16f588dde75a0c9c28175f16b8cb9e11dc" />
 
   <!-- COS sources -->
   <project path="src/overlays"