Commit
f25277e872d17f984d7480af119c12cf865758f2
by Pau Espin PedrolDrop unnecessary static initialization to NULL
Moreover, this callback was drepecated and is not ever called since
libosmocore.git 70ce871532ab21955e0955d7e230eae65438f047 (release 1.3.0).
See also libosmocore.git d31de237582f6fe3315d61bb9a488d4cda92654e.
Change-Id: I68ed65537eb6f33ef666a79ddef70b46c995e0e7