arm64: dts: imx8mm/n-venice-gw7902: Remove invalid property

The 'oscillator-frequency' property is not documented and it is
not used anywhere. Remove it.
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mm-venice-gw7902.dts

@@ -222,7 +222,6 @@ can@0 {
 		compatible = "microchip,mcp2515";
 		reg = <0>;
 		clocks = <&can20m>;
-		oscillator-frequency = <20000000>;
 		interrupt-parent = <&gpio2>;
 		interrupts = <3 IRQ_TYPE_LEVEL_LOW>;
 		spi-max-frequency = <10000000>;

arch/arm64/boot/dts/freescale/imx8mn-venice-gw7902.dts

@@ -213,7 +213,6 @@ can@0 {
 		compatible = "microchip,mcp2515";
 		reg = <0>;
 		clocks = <&can20m>;
-		oscillator-frequency = <20000000>;
 		interrupt-parent = <&gpio2>;
 		interrupts = <3 IRQ_TYPE_LEVEL_LOW>;
 		spi-max-frequency = <10000000>;