Fix hlsl pixel shader in multisampling demo

data/shaders/hlsl/multisampling/mesh.frag

@@ -1,7 +1,7 @@
 // Copyright 2020 Google LLC
 
-Texture2D textureColorMap : register(t1);
+Texture2D textureColorMap : register(t0, space1);
-SamplerState samplerColorMap : register(s1);
+SamplerState samplerColorMap : register(s0, space1);
 
 struct VSOutput
 {
@@ -20,7 +20,7 @@ float4 main(VSOutput input) : SV_TARGET
 	float3 L = normalize(input.LightVec);
 	float3 V = normalize(input.ViewVec);
 	float3 R = reflect(-L, N);
-	float3 diffuse = max(dot(N, L), 0.0) * input.Color;
+	float3 diffuse = max(dot(N, L), 0.15) * input.Color;
 	float3 specular = pow(max(dot(R, V), 0.0), 16.0) * float3(0.75, 0.75, 0.75);
 	return float4(diffuse * color.rgb + specular, 1.0);
 }