ftrace: Avoid redundant initialization in register_ftrace_direct

The FTRACE_OPS_FL_INITIALIZED flag is cleared in register_ftrace_direct,
which can make it initialized by ftrace_ops_init() even if it is already
initialized. It seems that there is no big deal here, but let's still fix
it.

Link: https://patch.msgid.link/20251110121808.1559240-1-dongml2@chinatelecom.cn
Fixes: f64dd46 ("ftrace: Add multi direct register/unregister interface")
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: image-dragon

kernel/trace/ftrace.c

@@ -6069,7 +6069,7 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
 	new_hash = NULL;
 
 	ops->func = call_direct_funcs;
-	ops->flags = MULTI_FLAGS;
+	ops->flags |= MULTI_FLAGS;
 	ops->trampoline = FTRACE_REGS_ADDR;
 	ops->direct_call = addr;