[dv] Fix regression compile error
[dv] Fix regression compile error

Some regression has compile error due to `cip_env` null object for
edn_agent_cfg. This PR fix it by adding a gating logic `has_edn` before
assigning zero_delay to it.

Signed-off-by: Cindy Chen <399ad771a111eac8923348b1e2af093034e5d4f1@google.com>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan