PHW_DEVICE_EXTENSION HwDeviceExtension,
      PVIDEO_HARDWARE_STATE HardwareState,
      ULONG HardwareStateSize

Routine Description:

    Restores all registers and memory of the VGA.

    Note: HardwareState points to the actual buffer from which the state
    is to be restored. This buffer will always be big enough (we specified
    the required size at DriverEntry).

    Note: The offset in the hardware state header from which each general
    register is restored is the offset of the write address of that register
    from the base I/O address of the VGA.

    !!! NOTE
    We assume the miniport and the display driver have UNLOCKED the extended
    registers so we can READ and WRITE them.


    HwDeviceExtension - Pointer to the miniport driver's device extension.

    HardwareState - Pointer to a structure from which the saved state is to be
        restored (actually only info about and a pointer to the actual save

    HardwareStateSize - Length of the input buffer supplied by the user.
        (Actually only the size of the HardwareState structure, not the
        buffer it points to from which the state is actually restored. The
        pointed-to buffer is assumed to be big enough.)

Return Value:

    NO_ERROR - restore performed successfully

    ERROR_INSUFFICIENT_BUFFER - input buffer not large enough to provide data