Align HW channel order with front panel

Currently, the hardware channel order (analog front-end) is a not consecutive and does not reflect the front panel order. The channels are re-mapped in HDL: https://ohwr.org/project/fsi-daq/blob/ML-fsi-det-8ch-v2/hdl/rtl/fsi/fsi_adc_rx.vhd

    -- tweak mapping of channels so that
    -- 1) gas cell (ch3) is seen on ch0
    -- 2) the other channels are physically aligned with the front panel
    --    (this means that the right most channel on the front panel
    --     is connected to the photodiod on the right of the board, etc...)
    --    This is to make the winding and attaching of the pigtail fibers
    --    more convenient
    data_o(0) <= fifo_dout(3 * 12 + 11 downto 3 * 12);
    data_o(1) <= fifo_dout(4 * 12 + 11 downto 4 * 12);
    data_o(2) <= fifo_dout(5 * 12 + 11 downto 5 * 12);
    data_o(3) <= fifo_dout(6 * 12 + 11 downto 6 * 12);
    data_o(4) <= fifo_dout(7 * 12 + 11 downto 7 * 12);
    data_o(5) <= fifo_dout(0 * 12 + 11 downto 0 * 12);
    data_o(6) <= fifo_dout(1 * 12 + 11 downto 1 * 12);
    data_o(7) <= fifo_dout(2 * 12 + 11 downto 2 * 12);

However, the AC/DC channel has special hardware and it cannot be re-mapped to match the front panel order. So, currently we have HW (on PCB) channels 1-7 in the "front panel order" and channel 0 on front panel connected to channel 7 on PCB.

This is not optimal for assembly. To avoid errors (and difficulty winding the fibers on the holder, the HW channels on PCB should be mapped 1-to-1 with the front panel channels.

In the v3 of the HW,do one of the following:

1. At minimum, move the AC/DC channel from position 7 (right of the PCB when looking from the front panel side) to the position 0 (left of the PCB)
2. Ideally, move other HW channels so that their order map 1-1 with the front panel order