Fix anisotropy.

This will be refactored as the needed array organization stabilize.

com.unity.render-pipelines.high-definition/HDRP/Material/StackLit/StackLit.hlsl

         preLightData.layeredRoughnessT[1] = bsdfData.roughnessBT;
         preLightData.layeredRoughnessB[1] = bsdfData.roughnessBB;
 
-        preLightData.iblPerceptualRoughness[0] = bsdfData.perceptualRoughnessA;
-        preLightData.iblPerceptualRoughness[1] = bsdfData.perceptualRoughnessB;
+        preLightData.iblPerceptualRoughness[BASE_LOBEA_IDX] = bsdfData.perceptualRoughnessA;
+        preLightData.iblPerceptualRoughness[BASE_LOBEB_IDX] = bsdfData.perceptualRoughnessB;
+        preLightData.iblAnisotropy[0] = bsdfData.anisotropy;
+        preLightData.iblAnisotropy[1] = bsdfData.anisotropy;
 
         float3 f0forCalculatingFGD = bsdfData.fresnel0;
         if (HasFlag(bsdfData.materialFeatures, MATERIALFEATUREFLAGS_STACK_LIT_IRIDESCENCE))
             // iblPerceptualRoughness is used as input and output here:
             GetGGXAnisotropicModifiedNormalAndRoughness(bsdfData.bitangentWS,
                 bsdfData.tangentWS,
-                N[BASE_NORMAL_IDX],
+                N[BASE_NORMAL_IDX], // N[] is sized one in this case here, so really N[0]
                 V,
                 preLightData.iblAnisotropy[0],
                 preLightData.iblPerceptualRoughness[BASE_LOBEA_IDX],