LoopFilterWorkerData: remove misleading 'const'

'frame_buffer' is modified indirectly via 'planes'.

+ do the same for vp9_loop_filter_rows

Change-Id: Ibb7daa2e261064e4a5317a2969e3490e59891b82

vp9/common/vp9_loopfilter.c

@@ -1193,7 +1193,7 @@ void vp9_filter_block_plane(VP9_COMMON *const cm,
   }
 }
 
-void vp9_loop_filter_rows(const YV12_BUFFER_CONFIG *frame_buffer,
+void vp9_loop_filter_rows(YV12_BUFFER_CONFIG *frame_buffer,
                           VP9_COMMON *cm,
                           struct macroblockd_plane planes[MAX_MB_PLANE],
                           int start, int stop, int y_only) {

vp9/common/vp9_loopfilter.h

@@ -111,13 +111,13 @@ void vp9_loop_filter_frame(YV12_BUFFER_CONFIG *frame,
                            int y_only, int partial_frame);
 
 // Apply the loop filter to [start, stop) macro block rows in frame_buffer.
-void vp9_loop_filter_rows(const YV12_BUFFER_CONFIG *frame_buffer,
+void vp9_loop_filter_rows(YV12_BUFFER_CONFIG *frame_buffer,
                           struct VP9Common *cm,
                           struct macroblockd_plane planes[MAX_MB_PLANE],
                           int start, int stop, int y_only);
 
 typedef struct LoopFilterWorkerData {
-  const YV12_BUFFER_CONFIG *frame_buffer;
+  YV12_BUFFER_CONFIG *frame_buffer;
   struct VP9Common *cm;
   struct macroblockd_plane planes[MAX_MB_PLANE];