tracing/kprobes: 'nmissed' not showed correctly for kretprobe

commit dfea08a2 upstream.

The 'nmissed' column of the 'kprobe_profile' file for kretprobe is
not showed correctly, kretprobe can be skipped by two reasons,
shortage of kretprobe_instance which is counted by tk->rp.nmissed,
and kprobe itself is missed by some reason, so to show the sum.

Link: https://lkml.kernel.org/r/20220107150242.5019-1-xyz.sun.ok@gmail.com

Cc: stable@vger.kernel.org
Fixes: 4a846b44

 ("tracing/kprobes: Cleanup kprobe tracer code")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Xiangyang Zhang <xyz.sun.ok@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>