tracing: Do not disable tracing when reading the trace file

When opening the "trace" file, it is no longer necessary to disable tracing.

Note, a new option is created called "pause-on-trace", when set, will cause
the trace file to emulate its original behavior.

Link: http://lkml.kernel.org/r/20200317213416.903351225@goodmis.org



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