[SCSI] zfcp: fix link down handling during firmware update

Don't check link down payload in case of firmware update.

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