ARM: dts: stm32: Add timer support for STM32F7

Add missing timer node to enable timer5 for STM32F7 SoCs family
Signed-off-by: NPatrice Chotard <patrice.chotard@st.com>

arch/arm/dts/stm32f7-u-boot.dtsi

+/{
+	soc {
+		timer5: timer@40000c00 {
+			u-boot,dm-pre-reloc;
+		};
+	};
+};
+
 &pinctrl {
 	usart1_pins_a: usart1@0	{
 		u-boot,dm-pre-reloc;

arch/arm/dts/stm32f746.dtsi

@@ -323,6 +323,13 @@
 			pinctrl-names = "default", "opendrain";
 			max-frequency = <48000000>;
 		};
+
+		timer5: timer@40000c00 {
+			compatible = "st,stm32-timer";
+			reg = <0x40000c00 0x400>;
+			interrupts = <50>;
+			clocks = <&rcc 0 STM32F7_APB1_CLOCK(TIM5)>;
+		};
 	};
 };