futility: updater: Revise error message when model is not defined in manifest

"Model '%s' is not defined in manifest." is not very easy to understand
for people who are debugging devices in early stages. We should provide
better instructions. For example, running with Coral updater will now
show:

ERROR: manifest_find_model: Cannot get model name.
You are probably running an image for wrong board, or a device in early
stage that 'mosys' command is not ready, or image from old (or factory)
branches that Unified Build config is not updated yet for 'mosys'.
Please check command 'mosys platform model', which should output one of
the supported models below:
 unprovisioned_meep sparky orbatrix unprovisioned_fleex grabbiter bobba
 unprovisioned_bobba mimrock fleex meep yorp phaser360 sparky360 phaser
 bobba360 unprovisioned_phaser bip

BUG=chromium:875551
TEST=TEST=make futil; tests/futility/run_test_scripts.sh $(pwd)/build/futility
BRANCH=None

Change-Id: Ib17fcb654d1530b94c44cf21aaa28717841f11ed
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1351171
Reviewed-by: Cheng-Han Yang <chenghan@chromium.org>
Reviewed-by: Ting Shen <phoenixshen@chromium.org>
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/1355750
Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Commit-Queue: Furquan Shaikh <furquan@chromium.org>
Tested-by: Furquan Shaikh <furquan@chromium.org>
Trybot-Ready: Furquan Shaikh <furquan@chromium.org>
2 files changed