ASoC: tegra20: spdif: make const array rates static

Don't populate the read-only const array rates on the stack but
instead it static. Also makes the object code a little smaller.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220214213223.65780-1-colin.i.king@gmail.com


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