[otbn] Explicitly stub off unused signal from tlul_adapter_sram
[otbn] Explicitly stub off unused signal from tlul_adapter_sram

This output port was added by 4798f27 but the commit didn't stub it
off for all uses in the tree. Fix the resulting OTBN lint warning.

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

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