drm/i915/guc: add dbgfs_node member kernel-doc

drivers/gpu/drm/i915/gt/uc/intel_guc.h:274: warning: Function parameter or member 'dbgfs_node' not described in 'intel_guc'
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b0f681dd82289dd86da78c6242411e8d812e51a1.1683041799.git.jani.nikula@intel.com

drivers/gpu/drm/i915/gt/uc/intel_guc.h

@@ -42,6 +42,7 @@ struct intel_guc {
 	/** @capture: the error-state-capture module's data and objects */
 	struct intel_guc_state_capture *capture;
 
+	/** @dbgfs_node: debugfs node */
 	struct dentry *dbgfs_node;
 
 	/** @sched_engine: Global engine used to submit requests to GuC */