iommu/vt-d: Drop the kernel doc annotation

Kernel doc validator is unhappy with the following

.../perf.c:16: warning: Function parameter or member 'latency_lock' not described in 'DEFINE_SPINLOCK'
.../perf.c:16: warning: expecting prototype for perf.c(). Prototype was for DEFINE_SPINLOCK() instead

Drop kernel doc annotation since the top comment is not in the required format.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210729163538.40101-1-andriy.shevchenko@linux.intel.comSigned-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210818134852.1847070-8-baolu.lu@linux.intel.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/perf.c

 // SPDX-License-Identifier: GPL-2.0
-/**
+/*
  * perf.c - performance monitor
  *
  * Copyright (C) 2021 Intel Corporation