drivers: usb: stm32: use generic LL headers

Use generic LL headers instead of depending on soc.h.

Signed-off-by: Martin Jäger <martin@libre.solar>
diff --git a/drivers/usb/device/usb_dc_stm32.c b/drivers/usb/device/usb_dc_stm32.c
index 1758752..f1b1807 100644
--- a/drivers/usb/device/usb_dc_stm32.c
+++ b/drivers/usb/device/usb_dc_stm32.c
@@ -45,6 +45,10 @@
  */
 
 #include <soc.h>
+#include <stm32_ll_bus.h>
+#include <stm32_ll_pwr.h>
+#include <stm32_ll_rcc.h>
+#include <stm32_ll_system.h>
 #include <string.h>
 #include <usb/usb_device.h>
 #include <drivers/clock_control/stm32_clock_control.h>
diff --git a/soc/arm/st_stm32/stm32l4/soc.h b/soc/arm/st_stm32/stm32l4/soc.h
index bd7c0b1..5ddffaa 100644
--- a/soc/arm/st_stm32/stm32l4/soc.h
+++ b/soc/arm/st_stm32/stm32l4/soc.h
@@ -41,11 +41,6 @@
 #include <stm32l4xx_ll_pwr.h>
 #endif /* CONFIG_CLOCK_CONTROL_STM32_CUBE */
 
-#ifdef CONFIG_USB
-/* Required to remove USB transceiver supply isolation */
-#include <stm32l4xx_ll_pwr.h>
-#endif /* CONFIG_USB */
-
 #endif /* !_ASMLANGUAGE */
 
 #endif /* _STM32L4X_SOC_H_ */