Add rudimentary STM32G0 USB PHY support

Author: thirtythreeforty

targets/TARGET_STM/USBPhyHw.h

@@ -47,6 +47,13 @@
 #define USBHAL_IRQn  USB_LP_IRQn
 #elif defined(TARGET_STM32F3)
 #define USBHAL_IRQn  USB_LP_CAN_RX0_IRQn
+#elif defined(TARGET_STM32G0)
+#define USB USB_DRD_FS
+#if defined(STM32G0B1xx)
+#define USBHAL_IRQn  USB_UCPD1_2_IRQn
+#else
+#define USBHAL_IRQn  USB_IRQn
+#endif
 #elif defined(TARGET_STM32L5)
 #define USBHAL_IRQn  USB_FS_IRQn
 #else

targets/targets.json

@@ -2939,8 +2939,14 @@
             "STM32G0B1xx"
         ],
         "device_has_add": [
-            "ANALOGOUT"
-        ]
+            "ANALOGOUT",
+            "USBDEVICE"
+        ],
+        "config": {
+            "usb_speed": {
+                "value": "USE_USB_NO_OTG"
+            }
+        }
     },
     "NUCLEO_G0B1RE": {
         "inherits": [