[M2351] Change default stdio-baud-rate to 115200

ccli8 · ccli8 · commit ad80ed17fc86 · 2020-01-06T15:55:00.000+08:00
diff --git a/platform/mbed_lib.json b/platform/mbed_lib.json
@@ -216,6 +216,9 @@
             "crash-capture-enabled": true,
             "fatal-error-auto-reboot-enabled": true
         },
+        "NU_PFM_M2351": {
+            "stdio-baud-rate": 115200
+        },
         "NRF52840_DK": {
             "crash-capture-enabled": true,
             "fatal-error-auto-reboot-enabled": true
