Small init fix

com.unity.render-pipelines.high-definition/HDRP/Lighting/LightLoop/LightLoopDef.hlsl

 {
     EnvLightData output;
     ZERO_INITIALIZE(EnvLightData, output);
+    output.lightLayers = 0xFFFFFFFF; // Enable sky for all layers
     output.influenceShapeType = ENVSHAPETYPE_SKY;
     // 31 bit index, 1 bit cache type
     output.envIndex = ENVCACHETYPE_CUBEMAP | (envIndex << 1);