Revert "small fix in case of grain_ids are provided as input"

This reverts commit 44ee3120.

5_reconstruction/gtSetupReconstruction.m

@@ -150,10 +150,6 @@ if isempty(conf.grain_ids)
     first = 1;
     last  = sample.phases{phaseID}.getNumberOfGrains();
     list = [first : last];
-else
-    first = 1;
-    last  = 1;
-    list  = conf.grain_ids;
 end