Files:
        APCB_CZN_D4.bin - Data only - No license, ABI or Version #

2021-04-05:
- Fix UMAmode
- Enable VBL/PSP to control eDP VDD.

2021-03-19:
- Remove all debug output

2021-03-18:
- Update DRQ routing

2021-03-11: Initial drop:
- Add APCB_CZN_D4.bin
    This is a data file that gives configuration data to AMD's ABL,
    the PSP AGESA Bootloader.  As there is no code, there is no ABI,
    license, or version number.

    Specified contents describing memory initialization:
    Memory is 2 channel, LPDDR4x

    The GPIOs to use for the SPD identifiers:
    Bit 0: GPIO 109
    Bit 1: GPIO 87
    Bit 2: GPIO 75
    Bit 3: GPIO 88

    SPDs from the guybrush platform:
    lp4x-spd-4.hex  # ID = 0(0b0000)  Parts = MT53E1G32D2NP-046 WT:A
    lp4x-spd-1.hex  # ID = 1(0b0001)  Parts = MT53E512M32D2NP-046 WT:F
    lp4x-spd-9.hex  # ID = 2(0b0010)  Parts = NT6AP256T32AV-J1
    All other GPIO IDs are unused.