ARM: dts: imx6ull-tarragon: Reduce SPI clock for QCA7000

Our hardware department recently informed us that, according to
the specification, the QCA7000 should be operated with a
maximum SPI clock frequency of 12 MHz. Even if it appears to work
at a higher frequency, we should not take any risks here. A short
performance test showed no measurable loss of speed.
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/nxp/imx/imx6ull-tarragon-master.dts

@@ -45,7 +45,7 @@ &pinctrl_qca700x_cp_rst
 		interrupts = <19 IRQ_TYPE_EDGE_RISING>;
 		spi-cpha;
 		spi-cpol;
-		spi-max-frequency = <16000000>;
+		spi-max-frequency = <12000000>;
 	};
 };
 
@@ -63,7 +63,7 @@ &pinctrl_qca700x_mains_rst
 		interrupts = <9 IRQ_TYPE_EDGE_RISING>;
 		spi-cpha;
 		spi-cpol;
-		spi-max-frequency = <16000000>;
+		spi-max-frequency = <12000000>;
 	};
 };
 

arch/arm/boot/dts/nxp/imx/imx6ull-tarragon-slave.dts

@@ -23,7 +23,7 @@ &pinctrl_qca700x_cp_rst
 		interrupts = <19 IRQ_TYPE_EDGE_RISING>;
 		spi-cpha;
 		spi-cpol;
-		spi-max-frequency = <16000000>;
+		spi-max-frequency = <12000000>;
 	};
 };
 

arch/arm/boot/dts/nxp/imx/imx6ull-tarragon-slavext.dts

@@ -45,7 +45,7 @@ &pinctrl_qca700x_cp_rst
 		interrupts = <19 IRQ_TYPE_EDGE_RISING>;
 		spi-cpha;
 		spi-cpol;
-		spi-max-frequency = <16000000>;
+		spi-max-frequency = <12000000>;
 	};
 };