[SCSI] hpsa: enable unit attention reporting

This used to be the default, but at some point the firmware guys
changed the default and I failed to notice.  Now to get unit
attention notifications, you must twiddle a bit indicating you
want them.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>