Read VBT from edk2/cbfs

[crawfxrd]

Do not embed the VBT binary into the driver.
Attempt to read it from edk2 FFS or cbfs.
This will make the driver the same for all models.

[crawfxrd]

This is how the file would be added in edk2:

FILE FREEFORM = 56752da9-de6b-4895-8819-1945b6b76c22 {
  SECTION RAW = vbt.rom
  SECTION UI = "IntelGopVbt"
}

We would need to read the raw section from the FV based on that GUID.

// LocateHandleBuffer: FirmwareVolume2Protocol
// for each handle:

gBS->OpenProtocol(
        <???>,                                  // Handle
        &gEfiFirmwareVolume2ProtocolGuid,       // Protocol
        &fv,                                    // Interface
        <???>,                                  // AgentHandle
        NULL,                                   // ControllerHandle
        EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL    // Attributes
);

fv->ReadSection(
    fv,                 // This
    VBT_FILE_GUID,      // NameGuid
    EFI_SECTION_RAW,    // SectionType
    0,                  // SectionInstance
    &buffer,            // Buffer
    &size,              // BufferSize
    &auth_status        // AuthenticationStatus
);

// if success, set VBT data and break

There's at least 2 FVs (UefiPayloadPkg.fdf) so we'd need to check all instances of EFI_FIRMWARE_VOLUME2_PROTOCOL.

Ref: UEFI-PI 1.9: III-3.4.1 Firmware Volume2 Protocol