boards: google_kukui: 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/google_kukui/google_kukui.dts

diff --git a/boards/arm/google_kukui/google_kukui.dts b/boards/arm/google_kukui/google_kukui.dts
index e4968a2..4fcb0d2 100644
--- a/boards/arm/google_kukui/google_kukui.dts
+++ b/boards/arm/google_kukui/google_kukui.dts
@@ -20,6 +20,17 @@
 	};
 };
 
+&clk_hsi {
+	status = "okay";
+};
+
+&rcc {
+	clocks = <&clk_hsi>;
+	clock-frequency = <DT_FREQ_M(8)>;
+	ahb-prescaler = <1>;
+	apb1-prescaler = <1>;
+};
+
 &usart1 {
 	pinctrl-0 = <&usart1_tx_pa9 &usart1_rx_pa10>;
 	current-speed = <115200>;

boards/arm/google_kukui/google_kukui_defconfig

diff --git a/boards/arm/google_kukui/google_kukui_defconfig b/boards/arm/google_kukui/google_kukui_defconfig
index b9e4b0c..798bb6b 100644
--- a/boards/arm/google_kukui/google_kukui_defconfig
+++ b/boards/arm/google_kukui/google_kukui_defconfig
@@ -24,12 +24,5 @@
 # GPIO Controller
 CONFIG_GPIO=y
 
-# Clock configuration
+# Enable Clocks
 CONFIG_CLOCK_CONTROL=y
-
-# Ideally, we would use HSI48, but this is not supported in
-# Zephyr. Use "basic" HSI (8 MHz).
-CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=8000000
-
-# SYSCLK selection
-CONFIG_CLOCK_STM32_SYSCLK_SRC_HSI=y