Merge patch series "Universal Payload initial series"

Simon Glass <[email protected]> says:

Universal Payload (UPL) is an Industry Standard for firmware
components[1]. UPL is designed to improve interoperability within the
firmware industry, allowing mixing and matching of projects with less
friction and fewer project-specific implementations. UPL is
cross-platform, supporting ARM, x86 and RISC-V initially.

This series provides some initial support for this, targeting 0.9.1 and
sandbox only.

Features still to come include:
- Support for architectures
- FIT validation
- Handoff validation
- Interoperability tests