LoongArchVirt: enable TPM2 support

[MarsDoge]

Summary

• add TPM 2.0 library mappings, PCDs, and conditional modules to the LoongArchVirt DSC so TPM2_ENABLE and TPM2_CONFIG_ENABLE provide full measurement and configuration flows
• include the corresponding Tcg2 PEI/DXE components in the LoongArchVirt firmware image layout

Testing

• build -b RELEASE -t GCC5 -a LOONGARCH64 -p OvmfPkg/LoongArchVirt/LoongArchVirtQemu.dsc -D TPM2_ENABLE=TRUE -D TPM2_CONFIG_ENABLE=TRUE (fails: BaseFdtLib dependency libfdt missing in workspace)

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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Select a real TPM instance instead of gEfiTpmDeviceInstanceNoneGuid

When TPM2_ENABLE is set the DSC still programs PcdTpmInstanceGuid to an all‑zero GUID, which corresponds to gEfiTpmDeviceInstanceNoneGuid. The TPM2 device router rejects any Tpm2DeviceLib whose provider GUID does not match this PCD, so the newly added Tpm2DeviceLibDTpm instance cannot register and every TPM call from Tcg2Pei/Tcg2Dxe will return EFI_UNSUPPORTED. The image therefore advertises TPM2 support but will never bind to an actual TPM device. PcdTpmInstanceGuid should be set to the GUID of the intended device (for QEMU this is typically gEfiTpmDeviceInstanceTpm20DtpmGuid) whenever TPM support is enabled.

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