drm/xe/mocs: Add debugfs node to dump mocs

This is useful to check mocs configuration. Tests/Tools can use
this debugfs entry to get mocs info.

v2: Address review comments. Change debugfs output style similar
to pat debugfs. (Lucas De Marchi)

v3: rebase.

v4: Address review comments. Use function pointer inside ops
struct. Update Test-with links. Remove usage of flags wherever
not required. (Lucas De Marchi)

v5: Address review comments. Move register defines. Modify mocs
info struct to avoid holes. (Luca De Marchi)

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Janga Rahul Kumar <janga.rahul.kumar@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240503193902.2056202-3-janga.rahul.kumar@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>