ply-utils: Drop ply_fd_can_take_data and ply_fd_may_block function
Drop ply_fd_can_take_data, because it is no longer be used now. drop ply_fd_may_block, because only ply_read_chunk use it, and ply_read_chunk has been removed in history.
Drop ply_fd_can_take_data, because it is no longer be used now. drop ply_fd_may_block, because only ply_read_chunk use it, and ply_read_chunk has been removed in history.