Controller will transfer only 32-bits on completion if it
knows we are only using 32-bit tags.  Also, some newer controllers
apparently (and erroneously) require that we only use 32-bit tags,
and that we inform the controller of this.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>