Answer is yes, even you can see 12c is listed under supported versions in document [888828.1].

However, there is a couple of buts (you should see this coming). Since latest  Exadata Storage Software (version does not have new offload libraries, smart scan offload filtering and storage indexes become disabled with 12c. Smart scans are initiated but nodes get back blocks instead of rows and columns in the projection list. Also IORM plans are not enforced and inter-database plans are disabled on cells. And finally, cell metrics display 12c databases under OTHER_DATABASE.

So, it seems better to wait until next Exadata update and probably 12c patch set update to upgrade your Exadata. At least, to be able upgrade to a fully functional state. Meanwhile, you'd better upgrade to if you haven't yet because upgrading from is not supported.