Fix double-callback-call crash in //chromeos/login/auth/

Fix bug found by the "bugprone-use-after-move" clang-tidy check.

Bug: 1122844
Change-Id: Icfdf8af891b11942d24bda43fb1e203333d3bd9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2556679
Commit-Queue: Achuith Bhandarkar <achuith@chromium.org>
Auto-Submit: Maksim Ivanov <emaxx@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Cr-Commit-Position: refs/heads/master@{#830608}

chromeos/login/auth/extended_authenticator_impl.cc

@@ -125,6 +125,7 @@ void ExtendedAuthenticatorImpl::OnFingerprintScanComplete(
   if (!reply) {
     std::move(callback).Run(cryptohome::CryptohomeErrorCode::
                                 CRYPTOHOME_ERROR_FINGERPRINT_ERROR_INTERNAL);
+    return;
   }
 
   std::move(callback).Run(reply->error());