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

include/ui/GraphicBuffer.h

@@ -63,6 +63,7 @@ public:
         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
     };