drivers: clock_control: stm32h5: Set HSI divider

By default HSIDIV is set to 0x01, so default frequency is 32 MHz.
This register should be always set based on dts value.

Signed-off-by: Wojciech Slenska <wsl@trackunit.com>

drivers/clock_control/clock_stm32_ll_h5.c

@@ -20,6 +20,9 @@
 #include <zephyr/drivers/clock_control/stm32_clock_control.h>
 
 /* Macros to fill up prescaler values */
+#define z_hsi_divider(v) LL_RCC_HSI_DIV_ ## v
+#define hsi_divider(v) z_hsi_divider(v)
+
 #define z_ahb_prescaler(v) LL_RCC_SYSCLK_DIV_ ## v
 #define ahb_prescaler(v) z_ahb_prescaler(v)
 
@@ -618,6 +621,8 @@ static void set_up_fixed_clock_sources(void)
 			/* Wait for HSI ready */
 			}
 		}
+		/* HSI divider configuration */
+		LL_RCC_HSI_SetDivider(hsi_divider(STM32_HSI_DIVISOR));
 	}
 
 	if (IS_ENABLED(STM32_LSE_ENABLED)) {