Update lowrisc_ip to lowRISC/opentitan@249b4c31
Update lowrisc_ip to lowRISC/opentitan@249b4c31

Update code from upstream repository
https://github.com/lowRISC/opentitan to revision
249b4c316cd6626d13e17edd8a52ca60c004af96

Since we deleted the lock file in the previous commit, this has no
shortlog, but note that the remote SHA matches that in the grandparent
commit (so we haven't missed anything).

Signed-off-by: Rupert Swarbrick <290093e2ad2515ed2f14d749293c8cf8e02ca274@lowrisc.org>

AmbiML/ibex,AmbiML/ibex,lowRISC/ibex,lowRISC/ibex,lowRISC/ibex,AmbiML/ibex,lowRISC/ibex,AmbiML/ibex