[otbn,dv] Add assertions to check I/DMEM SEC_WIPE
[otbn,dv] Add assertions to check I/DMEM SEC_WIPE

Added assertions are making sure that two things happen. First, a
secure wipe would trigger a change of key value in I/DMEM in which
the new value should come from URND. Second, after that change key
should change a second time, this time with valid being high and
value should come from OTP interface (meaning it is sideloaded).

Signed-off-by: Canberk Topal <e6b05429a51cc3258c31cb1f7836595b60921a29@lowrisc.org>

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