arch/arm/dts: Update Turris Mox device tree

Remove smi_pins definition since it is already in armada-37xx.dtsi.
Add assigned-clocks definitions to spi0.

Signed-off-by: Marek Behun <marek.behun@nic.cz>
Signed-off-by: Stefan Roese <sr@denx.de>

arch/arm/dts/armada-3720-turris-mox.dts

@@ -94,17 +94,13 @@
 	};
 };
 
-&pinctrl_sb {
-	smi_pins: smi-pins {
-		groups = "smi";
-		function = "smi";
-	};
-};
-
 &spi0 {
 	status = "okay";
 	pinctrl-names = "default";
 	pinctrl-0 = <&spi_cs1_pins>;
+	assigned-clocks = <&nb_periph_clk 7>;
+	assigned-clock-parents = <&tbg 1>;
+	assigned-clock-rates = <20000000>;
 
 	spi-flash@0 {
 		#address-cells = <1>;