nodedev: Fabric name must not be required for fc_host capability

fabric_name is one of many fc_host attributes in Linux that is optional
and left to the low-level driver to decide if it is implemented.
The zfcp device driver does not provide a fabric name for an fcp host.

This patch removes the requirement for a fabric name by making it optional.

Signed-off-by: Boris Fiuczynski <fiuczy@linux.vnet.ibm.com>

docs/formatnode.html.in

@@ -254,7 +254,7 @@
                 number of vport in use. <code>max_vports</code> shows the
                 maximum vports the HBA supports. "fc_host" implies following
                 sub-elements: <code>wwnn</code>, <code>wwpn</code>, and
-                <code>fabric_wwn</code>.
+                optionally <code>fabric_wwn</code>.
               </dd>
             </dl>
           </dd>

docs/news.xml

@@ -18,7 +18,18 @@
       <change/>
     </section>
     <section title="Bug fixes">
-      <change/>
+      <change>
+        <summary>
+          nodedev: Fabric name must not be required for fc_host capability
+        </summary>
+        <description>
+          fabric_name is one of many fc_host attributes in Linux that is
+          optional and left to the low-level driver to decide if it is
+          implemented. For example the zfcp device driver does not provide a
+          fabric name for an fcp host. The requirement for the existence of
+          a fabric name has been removed by making it optional.
+        </description>
+      </change>
     </section>
   </release>
   <release version="v3.0.0" date="2017-01-17">

docs/schemas/nodedev.rng

@@ -367,9 +367,11 @@
       <ref name='wwn'/>
     </element>
 
-    <element name='fabric_wwn'>
-      <ref name='wwn'/>
-    </element>
+    <optional>
+      <element name='fabric_wwn'>
+        <ref name='wwn'/>
+      </element>
+    </optional>
   </define>
 
   <define name='capsvports'>