samples/kprobes: Fix typo in handler_fault()

Fix a defective format in handler_fault() ending with an 'n' that
should be '\n'.

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/1621218083-23519-2-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Jonathan Corbet <corbet@lwn.net>