pistachio_marduk.dts: spi: enable quad mode

Enable the newly implemented spi quad mode. See change
79830c2.

Signed-off-by: Ian Pozella <[email protected]>

Author: Ham22

arch/mips/dts/pistachio_marduk.dts

@@ -58,6 +58,8 @@
 		reg = <1>;
 		spi-max-frequency = <50000000>;
 		nand-on-flash-bbt;
+		spi-rx-bus-width = <4>;
+		spi-tx-bus-width = <4>;
 		#address-cells = <1>;
 		#size-cells = <1>;
 	};