update riviera.hjson
update riviera.hjson

Signed-off-by: Dawid Zimonczyk <049f7e3b2b9716e0f331e21b3c38cae5a47562b7@aldec.com.pl>

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