Case formatting improvement

[dalance]

Case formatting improvement suggested at #580.

    always_ff @ (posedge clock) begin
        case (state)
            rx_IDLE :  sample_counter <= CLOCKS_PER_BAUD / 2;
            rx_SHIFT:  if ((sample_counter > 0)) begin
                           sample_counter <= sample_counter - 1;
                       end else begin
                           sample_counter <= CLOCKS_PER_BAUD - 1;
                       end
            rx_LOAD:   sample_counter <= 0;
            rx_DONE:   sample_counter <= 0;
        endcase
    end