ARM: dts: imx6: remove wrong spdif rxtx2 clock

The rxtx2 clock of i.MX6 S/PDIF is currently set to "asrc" clock.
However, according to SoC documentation, rxtx2 is connected to
ASRC_EXT_CLK, a different external clock.

Testing on Cubox-i system seems to confirm that: when fsl_spdif is
forced to select rxtx2 as input clock, audio playback fails with an I/O
error.

Set rxtx2 to the dummy clock by default to prevent fsl_spdif from
selecting it.
Signed-off-by: NAnssi Hannula <anssi.hannula@iki.fi>
Cc: Mark Brown <broonie@kernel.org>
Acked-by: NNicolin Chen <Guangyu.Chen@freescale.com>
Signed-off-by: NShawn Guo <shawn.guo@freescale.com>

arch/arm/boot/dts/imx6qdl.dtsi

@@ -181,7 +181,7 @@
 					       <&sdma 15 18 0>;
 					dma-names = "rx", "tx";
 					clocks = <&clks 197>, <&clks 3>,
-						 <&clks 197>, <&clks 107>,
+						 <&clks 197>, <&clks 0>,
 						 <&clks 0>,   <&clks 118>,
 						 <&clks 0>,  <&clks 139>,
 						 <&clks 0>;