Add 1880, 1882 Areca RAID bindings to arcmsr driver

NEWB PULL REQUEST (go easy, papers have been signed). 
Add in arcmsr driver bindings to the Areca ARC 1880 (from NexentaStor thread http://www.nexentastor.org/boards/1/topics/3278) and 1882 (my tests) RAID cards.