ASoC: wm_adsp: Move compr_attach/attached functions

Move wm_adsp_compr_attach and wm_adsp_compr_attached functions so they
will stay logically grouped with similar functions after some additional
changes.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>