ASoC: zx_aud96p22: make array aud96p22_dt_ids static

The array aud96p22_dt_ids is local to the source and does not need to be
in global scope, so make it static.

Cleans up sparse warning:
symbol 'aud96p22_dt_ids' was not declared. Should it be static?

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Mark Brown <broonie@kernel.org>