Photoshop: HSL Color picker plugin?

There is a plugin called HSBHSL provided by Adobe Photoshop itself. Hope that solve your problem.

HSBHSL The "HSL&HSB" plug-in allows conversion between RGB and HSL (Hue, Saturation, and Lightness) and between RGB and HSB (Hue, Saturation, and Brightness) within Photoshop. This plug-in also allows you to change the Hue, Saturation, or Luminosity of an image as independent channels. Or, to change HSL/HSB using channel operations (calculations).

Download here: Adobe Photoshop Optional Plugins