contrib: Add a quiet option to cros_update_firmware

Add a flag to reduce the amount of output that emerge
produces. Errors will still be sent to stdout.
BUG=none
TEST=Run script with and without options to confirm quieter output.

Change-Id: Ib49851ee495e253fc22058ff57f3895a9ba506a1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2249212
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Andrew McRae <amcrae@chromium.org>
Tested-by: Andrew McRae <amcrae@chromium.org>
1 file changed