[AIMIGRAPHX-1057] Fix TheRock multi-arch packaging: use Recommends for per-GPU dependencies

[kentqian]

Motivation

Multi-arch fat binary .deb packages currently declare all per-GPU runtime dependencies (amdrocm-dnn, amdrocm-blas) as hard Depends. This makes the package uninstallable on any system that doesn't have all GPU arch libraries available — even if the user only has one GPU type.

Technical Details

When MIGRAPHX_THEROCK_GPU_ARCH contains multiple architectures (e.g. gfx94x;gfx950;gfx110x;gfx120x), move per-GPU amdrocm-dnn/amdrocm-blas dependencies from Depends to Recommends (deb) / Suggests (rpm). Only the libraries matching the GPU actually present are needed at runtime.

• Single-arch builds are unchanged — per-GPU deps remain hard Depends.
• Also adds a device-all fallback path when MIGRAPHX_THEROCK_GPU_ARCH is empty.
• Removes the FATAL_ERROR guard so the therock backend can be used without specifying GPU arch.

Changelog Category

Add a CHANGELOG.md entry for any option other than Not Applicable

• • Added: New functionality.
• • Changed: Changes to existing functionality.
• • Removed: Functionality or support that has been removed. (Compared to a previous release)
• • Optimized: Component performance that has been optimized or improved.
• • Resolved Issues: Known issues from a previous version that have been resolved.
• • Not Applicable: This PR is not to be included in the changelog.

[Copilot]

Pull request overview

This PR adjusts TheRock packaging dependency metadata so multi-arch “fat binary” packages don’t become uninstallable by requiring all per-GPU runtime libraries as hard dependencies, while keeping single-arch behavior unchanged.

Changes:

• Removes the hard requirement that MIGRAPHX_THEROCK_GPU_ARCH must be set when using MIGRAPHX_PACKAGE_BACKEND=therock.
• For multi-arch builds, moves per-GPU amdrocm-dnn / amdrocm-blas dependencies from hard Depends into Recommends (deb) / Suggests (rpm).
• Adds an empty-arch “device-all” path that depends on arch-independent meta packages.