powerpc/devicetrees: Change 'gpios' to 'cs-gpios' on fsl, spi nodes

Since commit 0f0581b24b ("spi: fsl: Convert to use CS GPIO
descriptors"), the prefered way to define chipselect GPIOs is using
'cs-gpios' property instead of the legacy 'gpios' property.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7556683b57d8ce100855857f03d1cd3d2903d045.1574943062.git.christophe.leroy@c-s.fr

arch/powerpc/boot/dts/mgcoge.dts

@@ -224,7 +224,7 @@
 				reg = <0x11a80 0x40 0x89fc 0x2>;
 				interrupts = <2 8>;
 				interrupt-parent = <&PIC>;
-				gpios = < &cpm2_pio_d 19 0>;
+				cs-gpios = < &cpm2_pio_d 19 0>;
 				#address-cells = <1>;
 				#size-cells = <0>;
 				ds3106@1 {

arch/powerpc/boot/dts/mpc832x_rdb.dts

@@ -249,7 +249,7 @@
 			reg = <0x4c0 0x40>;
 			interrupts = <2>;
 			interrupt-parent = <&qeic>;
-			gpios = <&qe_pio_d 13 0>;
+			cs-gpios = <&qe_pio_d 13 0>;
 			mode = "cpu-qe";
 
 			mmc-slot@0 {

arch/powerpc/boot/dts/mpc8610_hpcd.dts

@@ -200,7 +200,7 @@
 			interrupts = <59 2>;
 			interrupt-parent = <&mpic>;
 			mode = "cpu";
-			gpios = <&sdcsr_pio 7 0>;
+			cs-gpios = <&sdcsr_pio 7 0>;
 			sleep = <&pmc 0x00000800 0>;
 
 			mmc-slot@0 {