tracing: Fix a typo in tracepoint.h

It should be @prev_pid, not @prev_prid.

Link: https://lkml.kernel.org/r/20210802140234.5383-1-shijie@os.amperecomputing.comSigned-off-by: Huang Shijie <shijie@os.amperecomputing.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

include/linux/tracepoint.h

@@ -475,7 +475,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
  *	*
  *	* The declared 'local variable' is called '__entry'
  *	*
- *	* __field(pid_t, prev_prid) is equivalent to a standard declaration:
+ *	* __field(pid_t, prev_pid) is equivalent to a standard declaration:
  *	*
  *	*	pid_t	prev_pid;
  *	*