drm/i915/pxp: fix kernel-doc for member dev_link

Add /** to make it a kernel-doc.

drivers/gpu/drm/i915/pxp/intel_pxp_types.h:96: warning: Function parameter or member 'dev_link' not described in 'intel_pxp'
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/84f89a3332fa323888f1e3241fb51ae10417ecd7.1683041799.git.jani.nikula@intel.com

drivers/gpu/drm/i915/pxp/intel_pxp_types.h

@@ -33,7 +33,9 @@ struct intel_pxp {
 	 */
 	struct i915_pxp_component *pxp_component;
 
-	/* @dev_link: Enforce module relationship for power management ordering. */
+	/**
+	 * @dev_link: Enforce module relationship for power management ordering.
+	 */
 	struct device_link *dev_link;
 	/**
 	 * @pxp_component_added: track if the pxp component has been added.