drm/i915/panel: Add missing parameters to kerneldoc

drivers/gpu/drm/i915/intel_panel.c:409: warning: Function parameter or member 'source_min' not described in 'scale'
drivers/gpu/drm/i915/intel_panel.c:409: warning: Function parameter or member 'source_max' not described in 'scale'
drivers/gpu/drm/i915/intel_panel.c:409: warning: Function parameter or member 'target_min' not described in 'scale'
drivers/gpu/drm/i915/intel_panel.c:409: warning: Function parameter or member 'target_max' not described in 'scale'

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180214091747.12753-1-chris@chris-wilson.co.uk
Link: https://patchwork.freedesktop.org/patch/msgid/20180214091747.12753-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_panel.c

@@ -397,8 +397,11 @@ intel_panel_detect(struct drm_i915_private *dev_priv)
 
 /**
  * scale - scale values from one range to another
- *
  * @source_val: value in range [@source_min..@source_max]
+ * @source_min: minimum legal value for @source_val
+ * @source_max: maximum legal value for @source_val
+ * @target_min: corresponding target value for @source_min
+ * @target_max: corresponding target value for @source_max
  *
  * Return @source_val in range [@source_min..@source_max] scaled to range
  * [@target_min..@target_max].