Add Ev into enums

com.unity.render-pipelines.high-definition/HDRP/Editor/Lighting/HDLightEditor.cs

         enum DirectionalLightUnit
         {
             Lux = LightUnit.Lux,
+            Ev = LightUnit.Ev,
         }
 
         enum AreaLightUnit
+            Ev = LightUnit.Ev,
         }
 
         enum PunctualLightUnit
+            Ev = LightUnit.Ev,
         }
 
         const float k_MinAreaWidth = 0.01f; // Provide a small size of 1cm for line light

com.unity.render-pipelines.high-definition/HDRP/Lighting/Light/HDAdditionalLightData.cs

         Candela,
         Lux,
         Luminance,
+        Ev,
     }
 
     // Light layering