Fix Keymaster HAL crash.

Test: VTS test validates this fix
Change-Id: I5996c2166cf4141c97424df64a380f45b001d52e
diff --git a/keymaster/3.0/default/KeymasterDevice.cpp b/keymaster/3.0/default/KeymasterDevice.cpp
index 58102bb..1c431bc 100644
--- a/keymaster/3.0/default/KeymasterDevice.cpp
+++ b/keymaster/3.0/default/KeymasterDevice.cpp
@@ -547,6 +547,7 @@
     if (!foundAttestationApplicationId) {
         _hidl_cb(ErrorCode::ATTESTATION_APPLICATION_ID_MISSING,
                  resultCertChain);
+        return Void();
     }
 
     keymaster_cert_chain_t cert_chain{nullptr, 0};