boards: stm32f072_eval: Use dts for clocks configuration

Convert board to use of device tree for clocks configuration.

Signed-off-by: Alexandre Bourdiol <alexandre.bourdiol@st.com>
diff --git a/boards/arm/stm32f072_eval/stm32f072_eval.dts b/boards/arm/stm32f072_eval/stm32f072_eval.dts
index 5e072e5..cfe8f2f 100644
--- a/boards/arm/stm32f072_eval/stm32f072_eval.dts
+++ b/boards/arm/stm32f072_eval/stm32f072_eval.dts
@@ -76,6 +76,25 @@
 	};
 };
 
+&clk_hse {
+	clock-frequency = <DT_FREQ_M(8)>;
+	status = "okay";
+};
+
+&pll {
+	prediv = <1>;
+	mul = <6>;
+	clocks = <&clk_hse>;
+	status = "okay";
+};
+
+&rcc {
+	clocks = <&pll>;
+	clock-frequency = <DT_FREQ_M(48)>;
+	ahb-prescaler = <1>;
+	apb1-prescaler = <1>;
+};
+
 &usart2 {
 	pinctrl-0 = <&usart2_tx_pd5 &usart2_rx_pd6>;
 	current-speed = <115200>;
diff --git a/boards/arm/stm32f072_eval/stm32f072_eval_defconfig b/boards/arm/stm32f072_eval/stm32f072_eval_defconfig
index 40a91d7..f35b570 100644
--- a/boards/arm/stm32f072_eval/stm32f072_eval_defconfig
+++ b/boards/arm/stm32f072_eval/stm32f072_eval_defconfig
@@ -6,9 +6,6 @@
 # Platform Configuration
 CONFIG_SOC_STM32F072XB=y
 
-# General Kernel Options
-CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=48000000
-
 # Serial Drivers
 CONFIG_SERIAL=y
 CONFIG_UART_INTERRUPT_DRIVEN=y
@@ -22,16 +19,5 @@
 # GPIO Controller
 CONFIG_GPIO=y
 
-# Clock configuration
+# Enable Clocks
 CONFIG_CLOCK_CONTROL=y
-# SYSCLK selection
-CONFIG_CLOCK_STM32_SYSCLK_SRC_PLL=y
-# HSE configuration
-CONFIG_CLOCK_STM32_HSE_CLOCK=8000000
-# PLL configuration
-CONFIG_CLOCK_STM32_PLL_SRC_HSE=y
-# produce 48MHz clock at PLL output
-CONFIG_CLOCK_STM32_PLL_PREDIV1=1
-CONFIG_CLOCK_STM32_PLL_MULTIPLIER=6
-CONFIG_CLOCK_STM32_AHB_PRESCALER=1
-CONFIG_CLOCK_STM32_APB1_PRESCALER=1