drm/xe/pf: Add debugfs to enable scheduler groups

drm/xe/pf: Add debugfs to enable scheduler groups

Reading the debugfs file lists the available configurations by name.
Writing the name of a configuration to the file will enable it.
Note that while this debugfs is PF-only, follow up patches will add some
debugfs files that are applicable to VF as well, so the function accepts
a vfid parameter to be ready for that.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patch.msgid.link/20251218223846.1146344-21-daniele.ceraolospurio@intel.com