fgraph: Correct typo in ftrace_return_to_handler comment

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250218122052.58348-1-haiyuewa@163.com


Signed-off-by: Haiyue Wang <haiyuewa@163.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>