ARM: dts: imx6qdl-gw5x: Remove unneeded 'fsl,mode' property

imx6qdl-gw5x boards use sgtl5000 codec and the machine file (imx-sgtl5000)
already sets SSI in slave mode and codec in master mode, so there is no need
for having this property.

Cc: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6qdl-gw52xx.dtsi

@@ -282,7 +282,6 @@ &pwm4 {
 };
 
 &ssi1 {
-	fsl,mode = "i2s-slave";
 	status = "okay";
 };
 

arch/arm/boot/dts/imx6qdl-gw53xx.dtsi

@@ -287,7 +287,6 @@ &pwm4 {
 };
 
 &ssi1 {
-	fsl,mode = "i2s-slave";
 	status = "okay";
 };
 

arch/arm/boot/dts/imx6qdl-gw54xx.dtsi

@@ -376,12 +376,10 @@ &pwm4 {
 };
 
 &ssi1 {
-	fsl,mode = "i2s-slave";
 	status = "okay";
 };
 
 &ssi2 {
-	fsl,mode = "i2s-slave";
 	status = "okay";
 };