ASoC: twl6040: Fix PCM error handling ops

This patch moves all the PCM error handling for clock config
out of trigger() and startup() and into prepare().

Signed-off-by: Margarita Olaya Cabrera <magi.olaya@ti.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>