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

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 <peter.chen@kernel.org>
Cc: Pawel Laszczak <pawell@cadence.com>
Cc: Roger Quadros <rogerq@kernel.org>
Cc: Aswath Govindraju <a-govindraju@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: linux-usb@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Acked-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210526130037.856068-11-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>