drm/xe/debugfs: Update xe_mocs_dump signature

drm/xe/debugfs: Update xe_mocs_dump signature

Our debugfs helper xe_gt_debugfs_show_with_rpm() expects print()
functions to return int. New signature allows us to drop wrapper.

While around, move kernel-doc closer to the function definition,
as suggested in the doc-guide.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://lore.kernel.org/r/20250923211613.193347-5-michal.wajdeczko@intel.com