ASoC: fsl: remove unneeded AUDMUX register setting from imx-sgtl5000

If we don't set IMX_AUDMUX_V2_PTCR_TCLKDIR in the AUDMUX PTCR
register (means Tx clock pin is input), we don't need to set
IMX_AUDMUX_V2_PTCR_TCSEL as well. Since both i.MX35, i.MX51 and
i.MX6 datasheet says "When Tx clock pin set as an input, the TCSEL
settings are ignored".

Signed-off-by: Hui Wang <jason77.wang@gmail.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>