clock_control: stm32_ll_clock: Enable MSI autocal when PLL source

Allow for the MSI to be auto-cal'd via an LSE when enabled, even when
being used as a source for the PLL as the sysclock.

Signed-off-by: Pushpal Sidhu <psidhu.devel@gmail.com>
diff --git a/drivers/clock_control/stm32_ll_clock.c b/drivers/clock_control/stm32_ll_clock.c
index b81bb43..cf9bb1b 100644
--- a/drivers/clock_control/stm32_ll_clock.c
+++ b/drivers/clock_control/stm32_ll_clock.c
@@ -273,6 +273,12 @@
 #endif /* CONFIG_CLOCK_STM32_PLL_Q_DIVISOR */
 
 #ifdef CONFIG_CLOCK_STM32_PLL_SRC_MSI
+
+#ifdef CONFIG_CLOCK_STM32_MSI_PLL_MODE
+	/* Enable MSI hardware auto calibration */
+	LL_RCC_MSI_EnablePLLMode();
+#endif
+
 	/* Switch to PLL with MSI as clock source */
 	LL_PLL_ConfigSystemClock_MSI(&s_PLLInitStruct, &s_ClkInitStruct);