ASoC: ab8500: Remove some leftover from the "Replace GPLv2 boilerplate/reference with SPDX" rules

The "Replace GPLv2 boilerplate/reference with SPDX" has left some empty
"License terms" paragraphs.
Remove them as well.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/28c0833d4a11f8f75f385e5aad93c23721b06c7e.1653724847.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Mark Brown <broonie@kernel.org>