[SCSI] zfcp: transport class adaptations

Added host stats, removed superfluous get_starget_ functions,
removed some attributes from zfcp specific sysfs tree (e.g.
scsi_host_no, scsi_lun, wwnn and d_id).
Host stats are given for the physical adapter port not for the
virtual adapter. Reset stats is implemented in the device driver.

Signed-off-by: Andreas Herrmann <aherrman@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>