ALSA: Remove some left-over license text in include/uapi/sound/

There is already a SPDX-License-Identifier tag, so the corresponding
license text can be removed.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/203c1db92c470925f31e361f6e7d180812501f2e.1664112023.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Takashi Iwai <tiwai@suse.de>