Camera: Add missing characteristics for using buffermanager in ExternalCamera

Buffer manager is used in the external camera, but the key is not included in the aidl.
Add a buffermanger key according to the key definition.

Test: Test with USB Camera
Change-Id: I8c8c35d933fecb14dcf39996c709b643db3ee3e3
diff --git a/camera/device/default/ExternalCameraDevice.cpp b/camera/device/default/ExternalCameraDevice.cpp
index 677fb42..649bf43 100644
--- a/camera/device/default/ExternalCameraDevice.cpp
+++ b/camera/device/default/ExternalCameraDevice.cpp
@@ -399,6 +399,10 @@
     const uint8_t hotPixelMode = ANDROID_HOT_PIXEL_MODE_OFF;
     UPDATE(ANDROID_HOT_PIXEL_AVAILABLE_HOT_PIXEL_MODES, &hotPixelMode, 1);
 
+    // android.info
+    const uint8_t bufMgrVer = ANDROID_INFO_SUPPORTED_BUFFER_MANAGEMENT_VERSION_HIDL_DEVICE_3_5;
+    UPDATE(ANDROID_INFO_SUPPORTED_BUFFER_MANAGEMENT_VERSION, &bufMgrVer, 1);
+
     // android.jpeg
     const int32_t jpegAvailableThumbnailSizes[] = {0,   0,   176, 144, 240, 144, 256,
                                                    144, 240, 160, 256, 154, 240, 180};