update_bootloaders: Remove board_specific_setup hook

No boards define a board_update_bootloaders function.  Take this hook
away before people start using it.

BUG=none
TEST=CQ

Change-Id: Ib4f78bd81e2b8eb2fb404176c4c7fb89e8ebda5a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/4864969
Reviewed-by: Greg Edelston <gredelston@google.com>
Tested-by: Jack Rosenthal <jrosenth@chromium.org>
Auto-Submit: Jack Rosenthal <jrosenth@chromium.org>
Commit-Queue: Greg Edelston <gredelston@google.com>
1 file changed