[SCSI] zfcp: remove undefined subtype for status read response

The status read response FSF_STATUS_READ_SUB_ERROR_PORT is not
defined in the specs and therefore not valid.
All occurrences are removed from the code.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>