Add getKeyCharacteristics stub to KeyMint

Add a stub implementation of getKeyCharacteristics which simply returns
UNIMPLEMENTED. A future change will replace this with a real
implementation.

(cherry picked from commit 8fa89b5538eb822790f0fb100e506d3b003d393d)

Bug: 186685601
Test: Treehugger
Ignore-AOSP-First: Implementation exists in internal master only
Merged-In: I5b33a48b90c0b7e28eb96ebbe099099661fc56de
Change-Id: I5b33a48b90c0b7e28eb96ebbe099099661fc56de
diff --git a/ng/AndroidKeyMintDevice.cpp b/ng/AndroidKeyMintDevice.cpp
index f9bc0b0..776a58a 100644
--- a/ng/AndroidKeyMintDevice.cpp
+++ b/ng/AndroidKeyMintDevice.cpp
@@ -410,6 +410,13 @@
     return kmError2ScopedAStatus(KM_ERROR_UNIMPLEMENTED);
 }
 
+ScopedAStatus AndroidKeyMintDevice::getKeyCharacteristics(
+    const std::vector<uint8_t>& /* storageKeyBlob */, const std::vector<uint8_t>& /* appId */,
+    const std::vector<uint8_t>& /* appData */,
+    std::vector<KeyCharacteristics>* /* keyCharacteristics */) {
+    return kmError2ScopedAStatus(KM_ERROR_UNIMPLEMENTED);
+}
+
 IKeyMintDevice* CreateKeyMintDevice(SecurityLevel securityLevel) {
     return ::new AndroidKeyMintDevice(securityLevel);
 }