image_signing: Remove legacy unified build feature

This feature was originally implemented before go/cros-unibuild-signing.
It only provided basis support to continue testing unibuilds, but didn't
deal with the actual required model specific cases.

Unibuilds have already been migrated away from this, so this feature is
now obsolete.

BUG=None
TEST=~/trunk/src/platform/vboot_reference/scripts/image_signing/sign_official_build.sh
recovery ../build/images/coral/latest/recovery_image.bin
../platform/vboot_reference/tests/devkeys
BRANCH=None

Change-Id: I58b569b97f0bf42a927a851e7bc0559cb1e26200
Reviewed-on: https://chromium-review.googlesource.com/660805
Commit-Ready: C Shapiro <shapiroc@google.com>
Tested-by: C Shapiro <shapiroc@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

scripts/image_signing/sign_official_build.sh

@@ -646,29 +646,6 @@ resign_firmware_payload() {
       done
       unset IFS
     } < "${signer_config}"
-  # TODO(shapiroc): Delete this case once the build is migrated to use
-  # signer_config.csv
-  elif [[ -d "${shellball_dir}/models" ]]; then
-    info "Signing firmware for all of the models in the unified build."
-    local model_dir
-    for model_dir in "${shellball_dir}"/models/*; do
-      local image_file sign_args=() loem_sfx loem_output_dir
-      for image_file in "${model_dir}"/bios*.bin; do
-        local model_name=$(sed -r 's:.*/models/(.*)/bios.*[.]bin$:\1:'\
-              <<<"${model_dir}")
-        if [[ -e "${KEY_DIR}/loem.ini" ]]; then
-          # Extract the extended details from "bios.bin" and use that, along
-          # with the model name, as the subdir for the keyset.
-          loem_sfx=$(sed -r "s:.*/models/${model_name}/bios([^/]*)[.]bin$:\1:"\
-                   <<<"${image_file}")
-          loem_output_dir="${shellball_dir}/keyset${loem_sfx}${model_name}"
-          sign_args=( "${loem_output_dir}" )
-          mkdir -p "${loem_output_dir}"
-        fi
-        sign_firmware "${image_file}" "${KEY_DIR}" "${FIRMWARE_VERSION}" \
-          "${sign_args[@]}"
-      done
-    done
   else
     local image_file sign_args=() loem_sfx loem_output_dir
     for image_file in "${shellball_dir}"/bios*.bin; do