rename controlif_setup() to ctrl_interface_setup()

which means that all control interface related functions now have
the common ctrl_ prefix.
diff --git a/src/ctrl/control_if.c b/src/ctrl/control_if.c
index bb690e5..54bca23 100644
--- a/src/ctrl/control_if.c
+++ b/src/ctrl/control_if.c
@@ -646,8 +646,8 @@
 	return 0;
 }
 
-struct ctrl_handle *controlif_setup(void *data, uint16_t port,
-					ctrl_cmd_lookup lookup)
+struct ctrl_handle *ctrl_interface_setup(void *data, uint16_t port,
+					 ctrl_cmd_lookup lookup)
 {
 	int ret;
 	struct ctrl_handle *ctrl;