Fix the build error below while keeping the current PREEMPT_RT code:

kernel/trace/trace_events_trigger.c: In function ‘stacktrace_trigger’:
kernel/trace/trace_events_trigger.c:1227:3: error: too many arguments to function ‘__trace_stack’
   __trace_stack(file->tr, flags, STACK_SKIP, preempt_count());
   ^~~~~~~~~~~~~
In file included from kernel/trace/trace_events_trigger.c:15:
kernel/trace/trace.h:826:6: note: declared here
 void __trace_stack(struct trace_array *tr, unsigned int trace_ctx, int skip);
      ^~~~~~~~~~~~~

Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>