Rollback flags: handle cases where flag values are negative

Handle cases where ENABLE_ROLLBACK_TIMEOUT and
ROLLBACK_LIFETIME_IN_MILLIS are negative. So that if the values are
negative, the default values will be assigned.

Fixes: 127925227
Test: atest RollbackTest
Change-Id: I416716a0070907394cd0f61cfcabf521cec77874
2 files changed