logind: make session_restore_vt() static

It's only used in logind-session.c.

src/login/logind-session.c

@@ -36,6 +36,7 @@
 #define RELEASE_USEC (20*USEC_PER_SEC)
 
 static void session_remove_fifo(Session *s);
+static void session_restore_vt(Session *s);
 
 int session_new(Session **ret, Manager *m, const char *id) {
         _cleanup_(session_freep) Session *s = NULL;
@@ -1223,7 +1224,7 @@ error:
         return r;
 }
 
-void session_restore_vt(Session *s) {
+static void session_restore_vt(Session *s) {
 
         static const struct vt_mode mode = {
                 .mode = VT_AUTO,

src/login/logind-session.h

@@ -173,7 +173,6 @@ const char* tty_validity_to_string(TTYValidity t) _const_;
 TTYValidity tty_validity_from_string(const char *s) _pure_;
 
 int session_prepare_vt(Session *s);
-void session_restore_vt(Session *s);
 void session_leave_vt(Session *s);
 
 bool session_is_controller(Session *s, const char *sender);