camera: Add external flash mode key

Test: CTS
Bug: 64847201
Change-Id: Ic99df793e4fe2b016c930c344eb64a264f004945
diff --git a/camera/metadata/3.3/types.hal b/camera/metadata/3.3/types.hal
index 3027555..09e0a9c 100644
--- a/camera/metadata/3.3/types.hal
+++ b/camera/metadata/3.3/types.hal
@@ -68,6 +68,14 @@
  * Enumeration definitions for the various entries that need them
  */
 
+/** android.control.aeMode enumeration values added since v3.2
+ * @see ANDROID_CONTROL_AE_MODE
+ */
+enum CameraMetadataEnumAndroidControlAeMode :
+        @3.2::CameraMetadataEnumAndroidControlAeMode {
+    ANDROID_CONTROL_AE_MODE_ON_EXTERNAL_FLASH,
+};
+
 /** android.control.captureIntent enumeration values added since v3.2
  * @see ANDROID_CONTROL_CAPTURE_INTENT
  */