perf/hw_breakpoint: Fix DocBook warnings in perf hw_breakpoint

Fix the following W=1 kernel build warning(s):

  kernel/events/hw_breakpoint.c:461: warning: Function parameter or member 'context' not described in 'register_user_hw_breakpoint'
  kernel/events/hw_breakpoint.c:560: warning: Function parameter or member 'context' not described in 'register_wide_hw_breakpoint'
Signed-off-by: Haocheng Xie <xiehaocheng.cn@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210527031947.1801-4-xiehaocheng.cn@gmail.com

kernel/events/hw_breakpoint.c

@@ -451,6 +451,7 @@ int register_perf_hw_breakpoint(struct perf_event *bp)
  * register_user_hw_breakpoint - register a hardware breakpoint for user space
  * @attr: breakpoint attributes
  * @triggered: callback to trigger when we hit the breakpoint
+ * @context: context data could be used in the triggered callback
  * @tsk: pointer to 'task_struct' of the process to which the address belongs
  */
 struct perf_event *
@@ -550,6 +551,7 @@ EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
  * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
  * @attr: breakpoint attributes
  * @triggered: callback to trigger when we hit the breakpoint
+ * @context: context data could be used in the triggered callback
  *
  * @return a set of per_cpu pointers to perf events
  */