ASoC: lpass-cpu: add module licence and description

This patch adds module licence to lpass-cpu driver, without this
patch lpass-cpu module would taint with below error:

snd_soc_lpass_cpu: module license 'unspecified' taints kernel.
Disabling lock debugging due to kernel taint
snd_soc_lpass_cpu: Unknown symbol regmap_write (err 0)
snd_soc_lpass_cpu: Unknown symbol devm_kmalloc (err 0)
...

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Kenneth Westfield <kwestfie@codeaurora.org>
Signed-off-by: Mark Brown <broonie@kernel.org>