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

Since commit 0f0581b24bd0 ("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 <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/7556683b[e-mail]

Documentation/devicetree/bindings/spi/fsl-spi.txt

···
 - clock-frequency : input clock frequency to non FSL_SOC cores
 
 Optional properties:
-- gpios : specifies the gpio pins to be used for chipselects.
+- cs-gpios : specifies the gpio pins to be used for chipselects.
   The gpios will be referred to as reg = <index> in the SPI child nodes.
   If unspecified, a single SPI device without a chip select can be used.
 - fsl,spisel_boot : for the MPC8306 and MPC8309, specifies that the
   SPISEL_BOOT signal is used as chip select for a slave device. Use
   reg = <number of gpios> in the corresponding child node, i.e. 0 if
-  the gpios property is not present.
+  the cs-gpios property is not present.
 
 Example:
 	spi@4c0 {
···
 		interrupts = <82 0>;
 		interrupt-parent = <700>;
 		mode = "cpu";
-		gpios = <&gpio 18 1	// device reg=<0>
-			 &gpio 19 1>;	// device reg=<1>
+		cs-gpios = <&gpio 18 1		// device reg=<0>
+			    &gpio 19 1>;	// device reg=<1>
 	};
 
 

arch/powerpc/boot/dts/mgcoge.dts

···
 				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

···
 			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

···
 			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 {