[SCSI] 3ware 9000 driver >4GB memory fix

The attached patch fixes a bug in the 3ware 9000 series driver:

- Fix use_sg == 0 mapping on systems with 4GB or higher.

  This fixes REPORT_LUNS (0xa0) failing with 3ware 9000 controllers on systems
  with lots of ram, mentioned in bugzilla # 6009:

      http://bugzilla.kernel.org/show_bug.cgi?id=6009



Signed-off-by: Adam Radford <linuxraid@amcc.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>