The option is there up until 8.1.1. It's undocumented though. Starting from 8.1.2 the option is no longer there, or is otherwise invisible.
san-1els01>
san-1els01> version
NetApp Release 8.1.1 7-Mode: Mon Jul 30 12:49:46 PDT 2012
san-1els01> options raid.disk.timeout.enable
raid.disk.timeout.enable ata@jake,fc,ata@ario,sata,sas,bsas,ssd,fsas (value might be overwritten in takeover)
san-1els01>
My best guess is that it's a list of drive types where the raid.timeout is enabled for. But that's just a WAG.