Fix onboard STLink uploading and debugging for Nucleo-Gxxx series (#509)

Author: maxgerhardt

boards/nucleo_g071rb.json

@@ -12,7 +12,13 @@
     "variant": "NUCLEO_G071RB"
   },
   "debug": {
+    "default_tools": [
+      "stlink"
+    ],
     "jlink_device": "STM32G071RB",
+    "onboard_tools": [
+      "stlink"
+    ],
     "openocd_target": "stm32g0x",
     "svd_path": "STM32G071.svd"
   },
@@ -27,8 +33,9 @@
   "upload": {
     "maximum_ram_size": 36864,
     "maximum_size": 131072,
-    "protocol": "mbed",
+    "protocol": "stlink",
     "protocols": [
+      "stlink",
       "jlink",
       "cmsis-dap",
       "blackmagic",

boards/nucleo_g431kb.json

@@ -12,7 +12,13 @@
     "can"
   ],
   "debug": {
+    "default_tools": [
+      "stlink"
+    ],
     "jlink_device": "STM32G431KB",
+    "onboard_tools": [
+      "stlink"
+    ],
     "openocd_target": "stm32g4x",
     "svd_path": "STM32G431xx.svd"
   },
@@ -26,8 +32,9 @@
   "upload": {
     "maximum_ram_size": 32768,
     "maximum_size": 131072,
-    "protocol": "mbed",
+    "protocol": "stlink",
     "protocols": [
+      "stlink",
       "jlink",
       "cmsis-dap",
       "blackmagic",

boards/nucleo_g431rb.json

@@ -12,7 +12,13 @@
     "can"
   ],
   "debug": {
+    "default_tools": [
+      "stlink"
+    ],
     "jlink_device": "STM32G431RB",
+    "onboard_tools": [
+      "stlink"
+    ],    
     "openocd_target": "stm32g4x",
     "svd_path": "STM32G431xx.svd"
   },
@@ -27,8 +33,9 @@
   "upload": {
     "maximum_ram_size": 32768,
     "maximum_size": 131072,
-    "protocol": "mbed",
+    "protocol": "stlink",
     "protocols": [
+      "stlink",
       "jlink",
       "cmsis-dap",
       "blackmagic",

boards/nucleo_g474re.json

@@ -12,7 +12,13 @@
     "can"
   ],
   "debug": {
+    "default_tools": [
+      "stlink"
+    ],
     "jlink_device": "STM32G474RE",
+    "onboard_tools": [
+      "stlink"
+    ],
     "openocd_target": "stm32g4x",
     "svd_path": "STM32G474xx.svd"
   },
@@ -28,8 +34,9 @@
   "upload": {
     "maximum_ram_size": 131072,
     "maximum_size": 524288,
-    "protocol": "mbed",
+    "protocol": "stlink",
     "protocols": [
+      "stlink",
       "jlink",
       "cmsis-dap",
       "blackmagic",