ASoC: sn95031: Pass CODEC to sn95031_jack_detection()

The sn95031 driver currently gets the CODEC implicitly from the jack that is
passed to sn95031_jack_detection(). But the codec field is going to be
removed from the snd_soc_jack struct, so refactor things to pass the CODEC
explicitly.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>