fs/resctrl: Disable BMEC event configuration when mbm_event mode is enabled

fs/resctrl: Disable BMEC event configuration when mbm_event mode is enabled

The BMEC (Bandwidth Monitoring Event Configuration) feature enables per-domain
event configuration. With BMEC the MBM events are configured using the
mbm_total_bytes_config or mbm_local_bytes_config files in

  /sys/fs/resctrl/info/L3_MON/

and the per-domain event configuration affects all monitor resource groups.

The mbm_event counter assignment mode enables counters to be assigned to RMID
(i.e. a monitor resource group), event pairs, with potentially unique event
configurations associated with every counter.

There may be systems that support both BMEC and mbm_event counter assignment
mode, but resctrl supporting both concurrently will present a conflicting
interface to the user with both per-domain and per RMID, event configurations
active at the same time.

The mbm_event counter assignment provides most flexibility to user space
and aligns with Arm's counter support. On systems that support both,
disable BMEC event configuration when mbm_event mode is enabled by hiding
the mbm_total_bytes_config or mbm_local_bytes_config files when mbm_event
mode is enabled. Ensure mon_features always displays accurate information
about monitor features.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Babu Moger <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com