ENGR00286961-3 ARM: dtsi: imx6qdl: Use non-default value for audmux pinctrl

ENGR00286961-3 ARM: dtsi: imx6qdl: Use non-default value for audmux pinctrl

It's better to specify pinctrl value so that we can clearly know what the
exact configuration they are. Also, when we need to set pinctrl state from
another state to default one, it must be given the exact values of pinctrl.

And this patch also sets TXD iomux to PUE keep. This would force TXD pin not
to pull down its signal during an unused state so that it won't distort its
output signal during that state.

Acked-by: Wang Shengjiu <b02247@freescale.com>
Signed-off-by: Nicolin Chen <b42378@freescale.com>