This fixes edd.c.  The SCSI changes replaced host_driverfs_dev with a
pointer to a struct device.  But, the Scsi_Host that the
edd_find_matching_scsi_device() was trying to get was never used anyway.
So, I removed it.

This also fixes a problem that I introduced a while ago, and that I
promised Matt I would fix: all attributes were getting added by default,
though they shouldn't be.  This regards only the truly default
attributes as default, and uses the test mechanism of the other
attributes to determine whether to add them or not.