Remove unnecessary and spammy NOTIMPLEMENTED() in AutofillClientIOS.

This method is called by the cross-platform autofill code resulting in
regular log spam. The calling sites don't expect a non-null return value
so there's no need to log this as an error.

BUG=658299

Review-Url: https://codereview.chromium.org/2435343002
Cr-Commit-Position: refs/heads/master@{#427081}

ios/chrome/browser/ui/autofill/autofill_client_ios.mm

@@ -56,9 +56,8 @@ PrefService* AutofillClientIOS::GetPrefs() {
   return browser_state_->GetPrefs();
 }
 
-// TODO(jdonnelly): Implement this when adding credit card upload.
+// TODO(crbug.com/535784): Implement this when adding credit card upload.
 syncer::SyncService* AutofillClientIOS::GetSyncService() {
-  NOTIMPLEMENTED();
   return nullptr;
 }