hardware: Add field for number of framebuffers supported

Change-Id: Iec29018a956d2c048ce077c48fd3995a4ca6f72a
diff --git a/include/hardware/fb.h b/include/hardware/fb.h
index ba2f286..135e4aa 100644
--- a/include/hardware/fb.h
+++ b/include/hardware/fb.h
@@ -64,7 +64,10 @@
     /* max swap interval supported by this framebuffer */
     const int       maxSwapInterval;
 
-    int reserved[8];
+    /* Number of framebuffers supported*/
+    const int       numFramebuffers;
+
+    int reserved[7];
 
     /*
      * requests a specific swap-interval (same definition than EGL)