ASoC: wm8994: fix add dynamic path error

If there don't exist dynamic sink or source widget, it will failed to
add dynamic path.

"AIF3ADCDAT" is snd_soc_dapm_aif_out, can't be dynamic sink widget. So
change the audio route to fix this issue.

Signed-off-by: Zidan Wang <zidan.wang@freescale.com>
Signed-off-by: Mark Brown <broonie@kernel.org>