fix missing common.read and common.write

as discussed in #463 `common.read` (and potentially `common.write`) is missing for optional states created by devices adapter. This is because of these two conditions...

Overwriting `common.read` if it is not `undefined` does not make much sense. The change will set it to `true` if `common.read` is  `undefined` (same for `common.write`).

Author: Garfonso

src-admin/src/Tabs/ListDevices.tsx

@@ -2458,12 +2458,12 @@ class ListDevices extends Component<ListDevicesProps, ListDevicesState> {
 
                         if (state.read !== undefined) {
                             common.read = state.read;
-                        } else if (common.read !== undefined) {
+                        } else if (common.read === undefined) {
                             common.read = true;
                         }
                         if (state.write !== undefined) {
                             common.write = state.write;
-                        } else if (common.write !== undefined) {
+                        } else if (common.write === undefined) {
                             common.write = true;
                         }