vty: Use vty_install_default() instead of bsc_install_default()

Remove ournode_exit_cmd, ournode_end_cmd, and bsc_install_default()
since this functionality is provided by the current libosmocore.

Replace calls to bsc_install_default() by call to
vty_install_default() with the following semantic patch:

    @rule1@
    expression N;
    @@
    - bsc_install_default(N);
    + vty_install_default(N);

Ticket: OW#952
Sponsored-by: On-Waves ehf
diff --git a/openbsc/src/libmsc/vty_interface_layer3.c b/openbsc/src/libmsc/vty_interface_layer3.c
index e0324d6..7869d5b 100644
--- a/openbsc/src/libmsc/vty_interface_layer3.c
+++ b/openbsc/src/libmsc/vty_interface_layer3.c
@@ -1002,7 +1002,7 @@
 
 	install_element(CONFIG_NODE, &cfg_mncc_int_cmd);
 	install_node(&mncc_int_node, config_write_mncc_int);
-	bsc_install_default(MNCC_INT_NODE);
+	vty_install_default(MNCC_INT_NODE);
 	install_element(MNCC_INT_NODE, &mnccint_def_codec_f_cmd);
 	install_element(MNCC_INT_NODE, &mnccint_def_codec_h_cmd);