sync: use manifest_name passed in

Commit fb527e3f52 ("sync: create dedicated
manifest project update func") refactored code from the main body into a
dedicated method.  The manifest_name was passed as an argument, but never
used it, and instead reaches back out to the command line options.  This
ignores the logic in the main loop where manifest_name might have changed
(like when using smart sync).

Change-Id: I4b84638fbb10c2b6f8f4b555e1475b0669c2daf4
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/305148
Reviewed-by: Raman Tenneti <rtenneti@google.com>
Tested-by: Mike Frysinger <vapier@google.com>

subcmds/sync.py

@@ -801,7 +801,7 @@ later is required to fix a server side protocol bug.
                              start, time.time(), clean)
       if not clean:
         sys.exit(1)
-      self._ReloadManifest(opt.manifest_name)
+      self._ReloadManifest(manifest_name)
       if opt.jobs is None:
         self.jobs = self.manifest.default.sync_j