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/osmo-bsc/osmo_bsc_vty.c b/openbsc/src/osmo-bsc/osmo_bsc_vty.c
index fceaa4a..4fac8ea 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_vty.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_vty.c
@@ -676,7 +676,7 @@
 	install_element(CONFIG_NODE, &cfg_net_bsc_cmd);
 
 	install_node(&bsc_node, config_write_bsc);
-	bsc_install_default(BSC_NODE);
+	vty_install_default(BSC_NODE);
 	install_element(BSC_NODE, &cfg_net_bsc_mid_call_text_cmd);
 	install_element(BSC_NODE, &cfg_net_bsc_mid_call_timeout_cmd);
 	install_element(BSC_NODE, &cfg_net_rf_socket_cmd);
@@ -686,7 +686,7 @@
 	install_element(BSC_NODE, &cfg_net_bsc_no_missing_msc_text_cmd);
 
 	install_node(&msc_node, config_write_msc);
-	bsc_install_default(MSC_NODE);
+	vty_install_default(MSC_NODE);
 	install_element(MSC_NODE, &cfg_net_bsc_token_cmd);
 	install_element(MSC_NODE, &cfg_net_bsc_ncc_cmd);
 	install_element(MSC_NODE, &cfg_net_bsc_mcc_cmd);