common.sh: drop unused DEFAULT_FAST

The last user was removed in CL:261260, so clean it up.

BUG=None
TEST=CQ passes

Change-Id: Id42954526dc305107af538b0de7aca49f5f818c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/1769240
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Alex Klein <saklein@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
1 file changed