[SCSI] mpt2sas: Support for greater than 2TB capacity WarpDrive

The driver is modified to allow access to the greater than 2TB WarpDrive
and properly handle direct-io mapping for WarpDrive volumes greater than 2TB.

Signed-off-by: Nagalakshmi Nandigama <nagalakshmi.nandigama@lsi.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>