vpn-manager: Remove unusued constant reported by clang.

BUG=chromium:309861
TEST=`FEATURES=test USE=clang emerge-lumpy crash-reporter`

Change-Id: I4877470c079eff2715deb3b69926f2fca96bd6d3
Reviewed-on: https://chromium-review.googlesource.com/173972
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Yunlian Jiang <yunlian@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
1 file changed