[otbn] Raise a fatal alert for incoming LC escalations
[otbn] Raise a fatal alert for incoming LC escalations

We specify that an incoming lifecycle escalation is handled in the
same way as any other fatal error, which raises a fatal alert. We didn't
do that in RTL yet so far.

Signed-off-by: Philipp Wagner <5a4b10454c30419e54a1570be358a516ff84bb63@lowrisc.org>

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