ARM: dts: stm32: update SPI6 dmas property on stm32mp157c

Remove unused parameter from SPI6 dmas property on stm32mp157c SoC.

Fixes: dc3f8c86c10d ("ARM: dts: stm32: add SPI support on stm32mp157c")
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
[olof: Without this patch, SPI6 will fall back to interrupt mode with
lower perfmance]
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/boot/dts/stm32mp157c.dtsi

@@ -1078,8 +1078,8 @@
 			interrupts = <GIC_SPI 86 IRQ_TYPE_LEVEL_HIGH>;
 			clocks = <&rcc SPI6_K>;
 			resets = <&rcc SPI6_R>;
-			dmas = <&mdma1 34 0x0 0x40008 0x0 0x0 0>,
-			       <&mdma1 35 0x0 0x40002 0x0 0x0 0>;
+			dmas = <&mdma1 34 0x0 0x40008 0x0 0x0>,
+			       <&mdma1 35 0x0 0x40002 0x0 0x0>;
 			dma-names = "rx", "tx";
 			status = "disabled";
 		};