Keep unrelated firmware in core rather than nowhere

An entry naming no RelatedItem was dropped from every category as soon
as any other entry named one, so core lost the bmc and uefi versions.

confluent_server/aiohmi/redfish/command.py

@@ -1360,19 +1360,15 @@ class Command(object):
         for res in results:
             entries.append((self._fwcategory(res[0]),
                             self._extract_fwinfo(res, labels)))
-        categorised = any(x[0] for x in entries)
         for fwcategory, res in entries:
             if res[0] is None:
                 continue
-            if wantcategory:
-                if categorised:
-                    if fwcategory != wantcategory:
-                        continue
-                elif wantcategory != 'core':
-                    # This platform does not say what any of its firmware
-                    # belongs to, and an uncategorised inventory on a bmc is
-                    # system firmware, so it can only answer for 'core'
-                    continue
+            # An entry that says nothing about what it belongs to is system
+            # firmware, which is what firmware on a bmc is unless it points at
+            # something else.  This holds for a whole inventory that names no
+            # relations and for the odd entry among ones that do.
+            if wantcategory and (fwcategory or 'core') != wantcategory:
+                continue
             yield res
 
     def _firmware_labels(self, results):