powerpc/82xx: remove spidev node from mgcoge

Commit 956b200a ("spi: spidev: Warn loudly if instantiated from DT
as "spidev"") states that there should not be spidev nodes in DTs.
Remove this non-HW description. There won't be a regression because it
won't bind since 2015 anyhow.

Fixes: 5d1d67e3 ("powerpc/82xx: add SPI support for mgcoge")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220824082130.21934-3-wsa+renesas@sang-engineering.com

arch/powerpc/boot/dts/mgcoge.dts

@@ -225,13 +225,6 @@ spi@11aa0 {
 				interrupts = <2 8>;
 				interrupt-parent = <&PIC>;
 				cs-gpios = < &cpm2_pio_d 19 0>;
-				#address-cells = <1>;
-				#size-cells = <0>;
-				ds3106@1 {
-					compatible = "gen,spidev";
-					reg = <0>;
-					spi-max-frequency = <8000000>;
-				};
 			};
 
 		};