[kmac,lint] Waive width mismatch warning in kmac_app.sv
[kmac,lint] Waive width mismatch warning in kmac_app.sv

When commit a3a2bc5 removed the explicit cast from the code, it
introduced a Verilator warning. Rather than introducing yet more
churn, just waive it.

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

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