ipaccess: Fix dropping the OML/RSL connection.

Use the ipaccess_drop_oml and ipaccess_drop_rsl functions
instead of closing the socket and hoping this is picked up
somehow. This just leads to some weird hangs. And gdb was
not really helpful to say where it was coming from.
diff --git a/openbsc/src/bsc_vty.c b/openbsc/src/bsc_vty.c
index aabb782..02d8b03 100644
--- a/openbsc/src/bsc_vty.c
+++ b/openbsc/src/bsc_vty.c
@@ -45,6 +45,7 @@
 #include <openbsc/system_information.h>
 #include <openbsc/debug.h>
 #include <openbsc/paging.h>
+#include <openbsc/ipaccess.h>
 
 #include "../bscconfig.h"
 
@@ -2299,13 +2300,11 @@
 
 	/* close all connections */
 	if (strcmp(argv[1], "oml") == 0) {
-		if (bts->oml_link)
-			close(bts->oml_link->ts->driver.ipaccess.fd.fd);
+		ipaccess_drop_oml(bts);
 	} else if (strcmp(argv[1], "rsl") == 0) {
 		/* close all rsl connections */
 		llist_for_each_entry(trx, &bts->trx_list, list) {
-			if (trx->rsl_link)
-				close(trx->rsl_link->ts->driver.ipaccess.fd.fd);
+			ipaccess_drop_rsl(trx);
 		}
 	} else {
 		vty_out(vty, "Argument must be 'oml# or 'rsl'.%s", VTY_NEWLINE);