block: Remove a no-op introduced by me and spotted by funman.

src/misc/block.c

@@ -245,8 +245,6 @@ struct block_fifo_t
 
 block_fifo_t *__block_FifoNew( vlc_object_t *p_obj )
 {
-    (void)p_obj;
-
     block_fifo_t *p_fifo;
 
     p_fifo = malloc( sizeof( block_fifo_t ) );