Revert "rcu: init rcu_registry_lock after fork"

This reverts commit 5243722376873a48e9852a58b91f4d4101ee66e4.
The patch forgot about rcu_sync_lock and was committed by mistake.

Reported-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

util/rcu.c

diff --git a/util/rcu.c b/util/rcu.c
index 47c2bce..8ba304d 100644
--- a/util/rcu.c
+++ b/util/rcu.c
@@ -335,11 +335,6 @@
     qemu_mutex_unlock(&rcu_registry_lock);
     qemu_mutex_unlock(&rcu_sync_lock);
 }
-
-static void rcu_init_child(void)
-{
-    qemu_mutex_init(&rcu_registry_lock);
-}
 #endif
 
 void rcu_after_fork(void)
@@ -351,7 +346,7 @@
 static void __attribute__((__constructor__)) rcu_init(void)
 {
 #ifdef CONFIG_POSIX
-    pthread_atfork(rcu_init_lock, rcu_init_unlock, rcu_init_child);
+    pthread_atfork(rcu_init_lock, rcu_init_unlock, rcu_init_unlock);
 #endif
     rcu_init_complete();
 }