Fix lightmap texture imports - likely copy-paste error

Source/Tools/AssetImporter/AssetImporter.cpp

@@ -1558,7 +1558,7 @@ void BuildAndSaveMaterial(aiMaterial* material, HashSet<String>& usedTextures)
     if (material->Get(AI_MATKEY_TEXTURE(aiTextureType_SPECULAR, 0), stringVal) == AI_SUCCESS)
         specularTexName = GetFileNameAndExtension(FromAIString(stringVal));
     if (material->Get(AI_MATKEY_TEXTURE(aiTextureType_LIGHTMAP, 0), stringVal) == AI_SUCCESS)
-        specularTexName = GetFileNameAndExtension(FromAIString(stringVal));
+        lightmapTexName = GetFileNameAndExtension(FromAIString(stringVal));
     if (material->Get(AI_MATKEY_TEXTURE(aiTextureType_EMISSIVE, 0), stringVal) == AI_SUCCESS)
         emissiveTexName = GetFileNameAndExtension(FromAIString(stringVal));
     if (!noMaterialDiffuseColor_)