Move out gtphub to its own subdir

Change-Id: I707d5e9b775179e732d281ce3d245de83d648eea
diff --git a/tests/gtphub/Makefile.am b/tests/gtphub/Makefile.am
index 523df61..fea01e0 100644
--- a/tests/gtphub/Makefile.am
+++ b/tests/gtphub/Makefile.am
@@ -31,7 +31,7 @@
 	$(NULL)
 
 gtphub_test_LDADD = \
-	$(top_builddir)/src/gprs/gtphub.o \
+	$(top_builddir)/src/gtphub/gtphub.o \
 	$(top_builddir)/src/gprs/gprs_utils.o \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOGSM_LIBS) \