display: Add BufferMirrorMode support for External

- In Buffer mirror mode, the output on the external should be rotated
  based on the primary orientation.
- this is used for the side sync feature.
- buffermirrormode has higher precedence over external orientation
- Add binder interface to enable/disable buffermirror mode

Change-Id: Ibea0af9627d69b4d42453adc868b113d82613437
diff --git a/libqservice/QService.cpp b/libqservice/QService.cpp
index f780a75..a8c5dca 100644
--- a/libqservice/QService.cpp
+++ b/libqservice/QService.cpp
@@ -77,6 +77,12 @@
     }
 }
 
+void QService::setBufferMirrorMode(uint32_t enable) {
+    if(mClient.get()) {
+        mClient->notifyCallback(BUFFER_MIRRORMODE, enable);
+    }
+}
+
 void QService::init()
 {
     if(!sQService) {