DF-1917 fix check (mrsas_ioctl.c:242-246 patched predicate):
  sgl_off=0x00000080 sge_count= 1 -> accepted (in-bounds)
  sgl_off=0x000003f8 sge_count= 1 -> accepted (in-bounds)
  sgl_off=0x000003fc sge_count= 1 -> REJECTED (EINVAL) -- would have OOB-written
  sgl_off=0x00000400 sge_count= 1 -> REJECTED (EINVAL) -- would have OOB-written
  sgl_off=0x000003fc sge_count=16 -> REJECTED (EINVAL) -- would have OOB-written
  sgl_off=0xffffffff sge_count= 1 -> REJECTED (EINVAL) -- would have OOB-written
  4/6 vectors rejected by the fix predicate.