Use proper clearcoat variable (#22839)

src/renderers/shaders/ShaderLib/meshphysical.glsl.js

@@ -181,7 +181,7 @@ void main() {
 
 		vec3 Fcc = F_Schlick( material.clearcoatF0, material.clearcoatF90, dotNVcc );
 
-		outgoingLight = outgoingLight * ( 1.0 - clearcoat * Fcc ) + clearcoatSpecular * clearcoat;
+		outgoingLight = outgoingLight * ( 1.0 - material.clearcoat * Fcc ) + clearcoatSpecular * material.clearcoat;
 
 	#endif