tracing/kprobes: Skip setup_boot_kprobe_events() when no cmdline event

tracing/kprobes: Skip setup_boot_kprobe_events() when no cmdline event

When the 'kprobe_event=' kernel command-line parameter is not provided,
there is no need to execute setup_boot_kprobe_events().

This change optimizes the initialization function init_kprobe_trace()
by skipping unnecessary work and effectively prevents potential blocking
that could arise from contention on the event_mutex lock in subsequent
operations.

Link: https://patch.msgid.link/20260204015401.163748-1-tianyaxiong@kylinos.cn
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Yaxiong Tian <tianyaxiong@kylinos.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>