Restored OTG clock enable in RCC in f107 usb init.

lib/usb/usb_f107.c

@@ -17,6 +17,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <libopencm3/stm32/rcc.h>
 #include <libopencm3/cm3/common.h>
 #include <libopencm3/stm32/tools.h>
 #include <libopencm3/stm32/otg_fs.h>
@@ -64,6 +65,7 @@ const struct _usbd_driver stm32f107_usb_driver = {
 /** Initialize the USB device controller hardware of the STM32. */
 static void stm32f107_usbd_init(void)
 {
+	rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_OTGFSEN);
 	OTG_FS_GINTSTS = OTG_FS_GINTSTS_MMIS;
 
 	OTG_FS_GUSBCFG |= OTG_FS_GUSBCFG_PHYSEL;