x86/AMD: distinguish compute units from hyper-threads

x86/AMD: distinguish compute units from hyper-threads

Fam17 replaces CUs by HTs, which we should reflect accordingly, even if
the difference is not very big. The most relevant change (requiring some
code restructuring) is that the topoext feature no longer means there is
a valid CU ID.

Take the opportunity and convert wrongly plain int variables in
set_cpu_sibling_map() to unsigned int.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Brian Woods <brian.woods@amd.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>