remove verity regardless of dm device

Changed the pattern substitution to work with dm-[0-9]

BUG=chromium-os:25441
TEST=Turned off verity on stumpy both with and without bootcache
BRANCH=none

Change-Id: I519ad71879f2db847f450b869c8f7a67606f1e20
Reviewed-on: https://gerrit.chromium.org/gerrit/38691
Tested-by: Paul Taysom <taysom@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: Paul Taysom <taysom@chromium.org>
1 file changed