SurfaceMediaSource: use the vid enc usage bit

This change makes SurfaceMediaSource add the VIDEO_ENC usage bit when
allocating its GraphicBuffers rather than the HW_TEXTURE bit.

Change-Id: Ie20e225c894fdbc31cad6bb82b3b64c7e98074eb
diff --git a/include/ui/GraphicBuffer.h b/include/ui/GraphicBuffer.h
index b9deafc..6ab01f4 100644
--- a/include/ui/GraphicBuffer.h
+++ b/include/ui/GraphicBuffer.h
@@ -63,6 +63,7 @@
         USAGE_HW_RENDER         = GRALLOC_USAGE_HW_RENDER,
         USAGE_HW_2D             = GRALLOC_USAGE_HW_2D,
         USAGE_HW_COMPOSER       = GRALLOC_USAGE_HW_COMPOSER,
+        USAGE_HW_VIDEO_ENCODER  = GRALLOC_USAGE_HW_VIDEO_ENCODER,
         USAGE_HW_MASK           = GRALLOC_USAGE_HW_MASK
     };