extcon: usbc-tusb320: fix kernel-doc warning

Fix the warning:
drivers/extcon/extcon-usbc-tusb320.c:19: warning: expecting prototype
for drivers/extcon/extcon-tusb320.c(). Prototype was for TUSB320_REG8()
instead
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Rong Chen <rong.a.chen@intel.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

drivers/extcon/extcon-usbc-tusb320.c

 // SPDX-License-Identifier: GPL-2.0
-/**
+/*
  * drivers/extcon/extcon-tusb320.c - TUSB320 extcon driver
  *
  * Copyright (C) 2020 National Instruments Corporation