Fix camera close sequencing.

Flush the device before disconnecting from it.
Hasn't caused identifiable bugs yet, but seems
dangerous and easy to fix.

TEST: builds & runs sample

Change-Id: Icaf27d4de5628087278b84bff586aab8e1e62e28
diff --git a/modules/camera/3_4/camera.cpp b/modules/camera/3_4/camera.cpp
index 30035bd..7f42eef 100644
--- a/modules/camera/3_4/camera.cpp
+++ b/modules/camera/3_4/camera.cpp
@@ -149,8 +149,8 @@
         return -EINVAL;
     }
 
-    disconnect();
     flush();
+    disconnect();
     mBusy = false;
     return 0;
 }