x86,fs/resctrl: Refactor domain create/remove using struct rdt_domain_hdr

x86,fs/resctrl: Refactor domain create/remove using struct rdt_domain_hdr

Up until now, all monitoring events were associated with the L3 resource and it
made sense to use the L3 specific "struct rdt_mon_domain *" argument to functions
operating on domains.

Telemetry events will be tied to a new resource with its instances represented
by a new domain structure that, just like struct rdt_mon_domain, starts with
the generic struct rdt_domain_hdr.

Prepare to support domains belonging to different resources by changing the
calling convention of functions operating on domains.  Pass the generic header
and use that to find the domain specific structure where needed.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com