ASoC: cs35l45: Relicense to GPL only

Cirrus never intended to upstream dual licensed code, convert to
GPL only.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Vlad Karpovich <vkarpovi@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230510092534.3919120-1-ckeepax@opensource.cirrus.com


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