Fix use-after-move in //chrome/browser/webauthn/

Fix use-after-move (potential) bugs found by the
"bugprone-use-after-move" clang-tidy check.

Bug: 1122844
Change-Id: I3065aa58a68b1f942a87e315906e0f0d2750c2c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2382318Reviewed-by: Adam Langley <agl@chromium.org>
Commit-Queue: Maksim Ivanov <emaxx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802901}

chrome/browser/webauthn/chrome_authenticator_request_delegate.cc

@@ -280,6 +280,7 @@ void ChromeAuthenticatorRequestDelegate::ShouldReturnAttestation(
     // This will require additional UI that is not yet ready. Therefore, at this
     // stage, it is always rejected.
     std::move(callback).Run(false);
+    return;
   }
 
   // Cryptotoken displays its own attestation consent prompt.