Remove some left-over from commit e2be04c7 ("License cleanup: add SPDX
license identifier to uapi header files with a license")

When the SPDX-License-Identifier tag has been added, the corresponding
license text has not been removed.

Remove it now.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>