MFC 254416:

  ------------------------------------------------------------------------
  r254416 | ken | 2013-08-16 10:14:32 -0600 (Fri, 16 Aug 2013) | 24 lines

  Add unmapped I/O and larger I/O support to the sa(4) driver.

  We now pay attention to the maxio field in the XPT_PATH_INQ CCB,
  and if it is set, propagate it up to physio via the si_iosize_max
  field in the cdev structure.

  We also now pay attention to the PIM_UNMAPPED capability bit in the
  XPT_PATH_INQ CCB, and set the new SI_UNMAPPED cdev flag when the
  underlying SIM supports unmapped I/O.

  scsi_sa.c:	Add unmapped I/O support and propagate the SIM's
  		maximum I/O size up.

  		Adjust scsi_tape_read_write() in the same way that
  		scsi_read_write() was changed to support unmapped
  		I/O.  We overload the readop parameter with bits
  		that tell us whether it's an unmapped I/O, and we
  		need to set the CAM_DATA_BIO CCB flag.  This change
  		should be backwards compatible in source and
  		binary forms.

  Sponsored by:	Spectra Logic