I just had a P411 show up in a DL580 G7 with this issue, and since I could not find any utility to set it back to RAID mode, I had to replace the controller.
If anyone knows of a utility that could be run from DOS or Linux (via any type of rescue boot media such as FreeDOS or Linux boot disk), that works on a ProLiant (similar to the saupdate EFI command on Integrity servers), this could avoid replacing what is theoretically a good, though misconfigured controller.
Dan