proto: Fix enum name mismatch

Servo FW channels can be stable,prev,dev,alpha

BUG=b:181711016
TEST=None

Change-Id: I20d7650c945b9fff4ac36c780916028fa17b2975
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2740430
Auto-Submit: Otabek Kasimov <otabek@google.com>
Reviewed-by: Xixuan Wu <xixuan@chromium.org>
Commit-Queue: Otabek Kasimov <otabek@google.com>
2 files changed