[SCSI] zfcp: correctly set this_id for hosts

It fixes a bug in zfcp which provokes a race
in scsi_scan.c. Finally this can lead to an Oops like:

kernel BUG at fs/sysfs/symlink.c:87!

Correctly set this_id for the host. Otherwise we provoke
a race between scsi_target_reap_work and concurrent
scsi_add_device.

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