fix lightning for inconsitent config

It's possible to configure to use the vertex color as lightning source without enabling the vertex color at all.
The old implementation will use zero, but it seems to be wrong (prooven by THPS3), more likely is to disable
the lightning and just return the global color.
This fixes THPS3 on OpenGL, but it isn't verifed on hardware

Source/Core/VideoCommon/Src/LightingShaderGen.h

@@ -150,7 +150,10 @@ static void GenerateLightingShader(T& object, LightingUidData& uid_data, int com
 				else if (components & VB_HAS_COL0 )
 					object.Write("lacc = %s0;\n", inColorName);
 				else
-					object.Write("lacc = float4(0.0f, 0.0f, 0.0f, 0.0f);\n");
+					// TODO: this isn't verified. Here we want to read the ambient from the vertex,
+					// but the vertex itself has no color. So we don't know which value to read.
+					// Returing 1.0 is the same as disabled lightning, so this could be fine
+					object.Write("lacc = float4(1.0f, 1.0f, 1.0f, 1.0f);\n");
 			}
 			else // from color
 			{
@@ -191,7 +194,8 @@ static void GenerateLightingShader(T& object, LightingUidData& uid_data, int com
 				else if (components & VB_HAS_COL0 )
 					object.Write("lacc.w = %s0.w;\n", inColorName);
 				else
-					object.Write("lacc.w = 0.0f;\n");
+					// TODO: The same for alpha: We want to read from vertex, but the vertex has no color
+					object.Write("lacc.w = 1.0f;\n");
 			}
 			else // from color
 			{