usb: dwc2: Remove redundant license text

SPDX-License-Identifier have been added in commit 5fd54ace ("USB: add
SPDX identifiers to all remaining files in drivers/usb/")

There is no point in keeping the now redundant license text.

Remove it.

Acked-by: Minas Harutyunyan <hminas@synopsys.com>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/030a7e187d707f8734a492cda7a6b54d459c4bb3.1662788747.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>