I reply to my own post just to let everybody know that I've found a way to manage my PERC H310 card with OMSA on 12th Gen servers. It's just a workaround, but it work: you have to uninstall OMSA 7.4.1 and install OMSA 7.0. 
Hello everybody, I have a Poweredge T320 with Perch H320 in a RHEL7.1 and OMSA 7.4.1, but I am unable to manage my storage card. I can see it listed under PCI devices, but the storage section say "No storage controller detected". Is there any OMSA upgrade or module to install, in order to manage my controller?
Perc H320 on OMSA 7.4.1