Ensure push_image is True for firmware branches.
Ensure push_image is True for firmware branches.

BUG=None
TEST=None

Change-Id: Idd3e3fe1669fd6c8f84d811592cae2fcc2f761f9
Reviewed-on: https://gerrit.chromium.org/gerrit/28889
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Commit-Ready: David McMahon <d7a8ce96a624b268d0a29e63bafad5dd5091190e@chromium.org>
Reviewed-by: David McMahon <d7a8ce96a624b268d0a29e63bafad5dd5091190e@chromium.org>
Tested-by: David McMahon <d7a8ce96a624b268d0a29e63bafad5dd5091190e@chromium.org>

bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,coreos/chromite,zhang0137/chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,coreos/chromite,chadversary/chromiumos.chromite,coreos/chromite