[SCSI] zfcp: fix: reopen port only if link-test fails

From: Maxim Shchetynin <maxim@de.ibm.com>

Reopen a remote port only if the link-test fails. This avoids that a
port is unnecessarily reopened.

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