tracing: Remove NULL check from current in tracing_generic_entry_update().

I can't imagine when or why `current' would return a NULL pointer. This
check was added in commit
      72829bc3 ("ftrace: move enums to ftrace.h and make helper function global")

but it doesn't give me hint why it was needed.

Assume `current' never returns a NULL pointer and remove the check.

Link: https://lkml.kernel.org/r/20210125194511.3924915-5-bigeasy@linutronix.deSigned-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

include/linux/trace_events.h

@@ -152,10 +152,8 @@ static inline void tracing_generic_entry_update(struct trace_entry *entry,
 						unsigned short type,
 						unsigned int trace_ctx)
 {
-	struct task_struct *tsk = current;
-
 	entry->preempt_count		= trace_ctx & 0xff;
-	entry->pid			= (tsk) ? tsk->pid : 0;
+	entry->pid			= current->pid;
 	entry->type			= type;
 	entry->flags =			trace_ctx >> 16;
 }