hsl: remove unused hsl_setup function

This function lives in openBSC not here.
diff --git a/src/input/hsl.c b/src/input/hsl.c
index 0bcde09..36061f5 100644
--- a/src/input/hsl.c
+++ b/src/input/hsl.c
@@ -405,12 +405,6 @@
 	return ret;
 }
 
-int hsl_setup(struct gsm_network *gsmnet)
-{
-	e1h->gsmnet = gsmnet;
-	return 0;
-}
-
 void e1inp_hsl_init(void)
 {
 	tall_hsl_ctx = talloc_named_const(libosmo_abis_ctx, 1, "hsl");