TextureCache: load all mipmap levels from custom textures

This drops the "feature" to load level 0 from the custom texture
and all other levels from the native one if the size matches.
But in my opinion, when a custom texture only provide one level,
no more should be used at all.

Source/Core/VideoCommon/PixelShaderManager.cpp

@@ -134,7 +134,7 @@ void PixelShaderManager::SetDestAlpha()
 	dirty = true;
 }
 
-void PixelShaderManager::SetTexDims(int texmapid, u32 width, u32 height, u32 wraps, u32 wrapt)
+void PixelShaderManager::SetTexDims(int texmapid, u32 width, u32 height)
 {
 	// TODO: move this check out to callee. There we could just call this function on texture changes
 	// or better, use textureSize() in glsl