[SCSI] zfcp: Clean up _zfcp_san_dbf_event_common_els

Clean up _zfcp_san_dbf_event_common_els using zfcp_dbf_hexdump()
helper.

Signed-off-by: Martin Peschke <mp3@de.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>