usb: cdns3: cdns3-imx: File headers are not good candidates for kernel-doc

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

drivers/usb/cdns3/cdns3-imx.c:21: warning: expecting prototype for cdns3(). Prototype was for USB3_CORE_CTRL1() instead

Cc: Peter Chen <[e-mail]>
Cc: Pawel Laszczak <[e-mail]>
Cc: Roger Quadros <[e-mail]>
Cc: Aswath Govindraju <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Shawn Guo <[e-mail]>
Cc: Sascha Hauer <[e-mail]>
Cc: Pengutronix Kernel Team <[e-mail]>
Cc: Fabio Estevam <[e-mail]>
Cc: NXP Linux Team <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Acked-by: Peter Chen <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/cdns3/cdns3-imx.c

···
 // SPDX-License-Identifier: GPL-2.0
-/**
+/*
  * cdns3-imx.c - NXP i.MX specific Glue layer for Cadence USB Controller
  *
  * Copyright (C) 2019 NXP