tracing: Add tp_printk_stop_on_boot option

Add a kernel command line option that disables printing of events to
console at late_initcall_sync(). This is useful when needing to see
specific events written to console on boot up, but not wanting it when
user space starts, as user space may make the console so noisy that the
system becomes inoperable.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>