Added copyright notice to a single file in the eigen_soc subdirectory

eigen_soc/hsohelp.F90

+!--------------------------------------------------------------------------------
+! Copyright (c) 2016 Peter Grünberg Institut, Forschungszentrum Jülich, Germany
+! This file is part of FLEUR and available as free software under the conditions
+! of the MIT license as expressed in the LICENSE file in more detail.
+!--------------------------------------------------------------------------------
+
 MODULE m_hsohelp
   !
   !*********************************************************************