ASoC: codecs: make snd_soc_platform_driver const

Make these const as they are either passed as the 2nd argument to the
function devm_snd_soc_register_platform or snd_soc_register_platform,
and the arguments are of type const.
Done using Coccinelle.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>