platforms/blackpill-f4: Fix DWC USB init (cleanup)

V-Bus Sense Disable is required both in DFU and in FW.

Author: ALTracer

src/platforms/common/blackpill-f4/blackpill-f4.c

@@ -80,15 +80,9 @@ void platform_init(void)
 	rcc_periph_clock_enable(RCC_OTGFS);
 	rcc_periph_clock_enable(RCC_CRC);
 
-#if 0
-	/* Set up USB Pins and alternate function */
-	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO9 | GPIO11 | GPIO12);
-	gpio_set_af(GPIOA, GPIO_AF10, GPIO9 | GPIO10 | GPIO11 | GPIO12);
-#else
-	/* PA9/PA10 are not routed to USB on Blackpill-F4 */
+	/* Set up DM/DP pins. PA9/PA10 are not routed to USB-C. */
 	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO11 | GPIO12);
 	gpio_set_af(GPIOA, GPIO_AF10, GPIO11 | GPIO12);
-#endif
 
 	GPIOA_OSPEEDR &= 0x3c00000cU;
 	GPIOA_OSPEEDR |= 0x28000008U;

src/platforms/common/blackpill-f4/usbdfu.c

@@ -73,11 +73,9 @@ int main(void)
 	dfu_protect(false);
 	dfu_init(&USB_DRIVER);
 
-#if 0
 	/* https://github.com/libopencm3/libopencm3/pull/1256#issuecomment-779424001 */
 	OTG_FS_GCCFG |= OTG_GCCFG_NOVBUSSENS | OTG_GCCFG_PWRDWN;
 	OTG_FS_GCCFG &= ~(OTG_GCCFG_VBUSBSEN | OTG_GCCFG_VBUSASEN);
-#endif
 
 	dfu_main();
 }