Remove incorrect system_fbo overwrite

drivers/gles3/storage/texture_storage.cpp

@@ -61,8 +61,6 @@ static const GLenum _cube_side_enum[6] = {
 TextureStorage::TextureStorage() {
 	singleton = this;
 
-	system_fbo = 0;
-
 	{ //create default textures
 		{ // White Textures