boards: nucleo_f303re: Use dts for clocks configuration

Convert board to use of device tree for clocks configuration.

Signed-off-by: Alexandre Bourdiol <alexandre.bourdiol@st.com>

boards/arm/nucleo_f303re/nucleo_f303re.dts

@@ -43,6 +43,27 @@
 	};
 };
 
+&clk_hse {
+	hse-bypass;
+	clock-frequency = <DT_FREQ_M(8)>; /* STLink 8MHz clock */
+	status = "okay";
+};
+
+&pll {
+	prediv = <1>;
+	mul = <9>;
+	clocks = <&clk_hse>;
+	status = "okay";
+};
+
+&rcc {
+	clocks = <&pll>;
+	clock-frequency = <DT_FREQ_M(72)>;
+	ahb-prescaler = <1>;
+	apb1-prescaler = <2>;
+	apb2-prescaler = <1>;
+};
+
 &usart2 {
 	pinctrl-0 = <&usart2_tx_pa2 &usart2_rx_pa3>;
 	current-speed = <115200>;

boards/arm/nucleo_f303re/nucleo_f303re_defconfig

@@ -2,8 +2,6 @@
 
 CONFIG_SOC_SERIES_STM32F3X=y
 CONFIG_SOC_STM32F303XE=y
-# 72 MHz system clock
-CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=72000000
 
 CONFIG_SERIAL=y
 
@@ -23,20 +21,5 @@ CONFIG_PINMUX=y
 # enable GPIO
 CONFIG_GPIO=y
 
-# clock configuration
+# Enable Clocks
 CONFIG_CLOCK_CONTROL=y
-
-# Clock configuration for Cube Clock control driver
-CONFIG_CLOCK_STM32_HSE_CLOCK=8000000
-CONFIG_CLOCK_STM32_SYSCLK_SRC_PLL=y
-# use HSE as PLL input
-CONFIG_CLOCK_STM32_PLL_SRC_HSE=y
-# however, the board does not have an external oscillator, so just use
-# the 8MHz clock signal coming from integrated STLink
-CONFIG_CLOCK_STM32_HSE_BYPASS=y
-# produce 72MHz clock at PLL output
-CONFIG_CLOCK_STM32_PLL_PREDIV1=1
-CONFIG_CLOCK_STM32_PLL_MULTIPLIER=9
-CONFIG_CLOCK_STM32_AHB_PRESCALER=1
-CONFIG_CLOCK_STM32_APB1_PRESCALER=2
-CONFIG_CLOCK_STM32_APB2_PRESCALER=1