[otbn, dv] Fixes edn_urnd_req_d issue in otbn_core_model
[otbn, dv] Fixes edn_urnd_req_d issue in otbn_core_model

This commit makes sure that edn_urnd_req_d is asserted only if Execute
comand is written into the cmd register only when in idle state.

Signed-off-by: Prajwala Puttappa <d42da9c1e7c0c7ddf8c0244ff16e57febc9395a0@lowrisc.org>

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