x86/cpufeatures: Add X86_FEATURE_AMD_WORKLOAD_CLASS feature bit

Add a new feature bit that indicates support for workload-based heuristic
feedback to OS for scheduling decisions.

When the bit set, threads are classified during runtime into enumerated
classes. The classes represent thread performance/power characteristics
that may benefit from special scheduling behaviors.

Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20241028020251.8085-4-mario.limonciello@amd.com