e1_input.h: Remove dead declaration of unexistent API ipaccess_setup

The function was removed long time ago in
af8ed983ffa1f750e3972e0fb850c16249943543.

Change-Id: I34debe01d1d8b6f4420354666d2a25807dacc25c
diff --git a/include/osmocom/abis/e1_input.h b/include/osmocom/abis/e1_input.h
index 1a701f9..3fbce5b 100644
--- a/include/osmocom/abis/e1_input.h
+++ b/include/osmocom/abis/e1_input.h
@@ -303,9 +303,6 @@
 
 int e1inp_vty_init(void);
 
-struct gsm_network;
-int ipaccess_setup(struct gsm_network *gsmnet);
-
 /* activate superchannel or deactive to use timeslots. only valid for unixsocket driver */
 void e1inp_ericsson_set_altc(struct e1inp_line *unixlinue, int superchannel);