vp9_decodeframe: simplify init_read_bit_buffer signature

Change-Id: I342075eb5a4ba2a85d36d47ae52d1f3476039e31

vp9/decoder/vp9_decodeframe.c

@@ -1926,12 +1926,12 @@ static void debug_check_frame_counts(const VP9_COMMON *const cm) {
 }
 #endif  // NDEBUG
 
-static struct vp9_read_bit_buffer* init_read_bit_buffer(
+static struct vp9_read_bit_buffer *init_read_bit_buffer(
     VP9Decoder *pbi,
     struct vp9_read_bit_buffer *rb,
     const uint8_t *data,
     const uint8_t *data_end,
-    uint8_t *clear_data /* buffer size MAX_VP9_HEADER_SIZE */) {
+    uint8_t clear_data[MAX_VP9_HEADER_SIZE]) {
   rb->bit_offset = 0;
   rb->error_handler = error_handler;
   rb->error_handler_data = &pbi->common;