ARM: dts: stm32: convert stm32mp2 board to OF_UPSTREAM

Enable OF_UPSTREAM flag for STM32MP2 platforms.
Add fixed-clock ck_flexgen_08 and ck_icn_ls_mcu until STM32MP25
clock driver will be available.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/arch/arm/dts/stm32mp257f-ev1-u-boot.dtsi b/arch/arm/dts/stm32mp257f-ev1-u-boot.dtsi
index a35a9b9..3beeaa1 100644
--- a/arch/arm/dts/stm32mp257f-ev1-u-boot.dtsi
+++ b/arch/arm/dts/stm32mp257f-ev1-u-boot.dtsi
@@ -5,8 +5,73 @@
 
 #include "stm32mp25-u-boot.dtsi"
 
+/ {
+	clocks {
+		ck_flexgen_08: ck-flexgen-08 {
+			#clock-cells = <0>;
+			compatible = "fixed-clock";
+			clock-frequency = <64000000>;
+		};
+
+		ck_icn_ls_mcu: ck-icn-ls-mcu {
+			#clock-cells = <0>;
+			compatible = "fixed-clock";
+			clock-frequency = <200000000>;
+		};
+	};
+};
+
+&gpioa {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpiob {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpioc {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpiod {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpioe {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpiof {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpiog {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpioh {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpioi {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpioj {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpiok {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
+&gpioz {
+	clocks = <&ck_icn_ls_mcu>;
+};
+
 &usart2 {
 	bootph-all;
+	clocks = <&ck_flexgen_08>;
 };
 
 &usart2_pins_a {