ExternalCameraHAL: Add ANDROID_SENSOR_READOUT_TIMESTAMP key.

As ExternalCameraHAL does not support sensor readout timestamp,
it should set ANDROID_SENSOR_READOUT_TIMESTAMP to
ANDROID_SENSOR_READOUT_TIMESTAMP_NOT_SUPPORTED in CameraDevice
characteristics.

This CL adds the CameraMetadata entry to ExternalCameraDevice.

Bug: 309543399
Test: ReadoutTimestampTest#testReadoutTimestamp passes for
      ExternalCameraHAL
Change-Id: I12203f0832416b4ca325380e671675ddc1d788d4
diff --git a/camera/device/default/ExternalCameraDevice.cpp b/camera/device/default/ExternalCameraDevice.cpp
index 649bf43..8e84748 100644
--- a/camera/device/default/ExternalCameraDevice.cpp
+++ b/camera/device/default/ExternalCameraDevice.cpp
@@ -497,6 +497,9 @@
     const int32_t maxLatency = ANDROID_SYNC_MAX_LATENCY_UNKNOWN;
     UPDATE(ANDROID_SYNC_MAX_LATENCY, &maxLatency, 1);
 
+    const uint8_t sensorReadoutTimestamp = ANDROID_SENSOR_READOUT_TIMESTAMP_NOT_SUPPORTED;
+    UPDATE(ANDROID_SENSOR_READOUT_TIMESTAMP, &sensorReadoutTimestamp, 1);
+
     /* Other sensor/RAW related keys:
      * android.sensor.info.colorFilterArrangement -> no need if we don't do RAW
      * android.sensor.info.physicalSize           -> not available
@@ -1002,4 +1005,4 @@
 }  // namespace device
 }  // namespace camera
 }  // namespace hardware
-}  // namespace android
\ No newline at end of file
+}  // namespace android