ASoC: cs4271: switch to mute_stream

Use the newly introduced mute_stream DAI operation, and don't mute the
codec if it's called for the _CAPTURE stream.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Alexander Sverdlin <subaparts@yandex.ru>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>