ASoC: rt5670: fix wrong audio route

When we select "IF1_ADC4" for IF1 ADC Muxes, it is actually connected
to "TxDP_ADC" widget. This patch fixes the audio route and remove the
unexisting "IF1_ADC4" widget.

Signed-off-by: Bard Liao <bardliao@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>