STM32_FAMILY: remove tickless-from-us-ticker and enable tickless

LMESTM · LMESTM · commit d56a96a5418d · 2019-05-29T11:22:25.000+02:00
diff --git a/targets/targets.json b/targets/targets.json
@@ -1880,8 +1880,7 @@
             }
         },
         "overrides": {
-            "deep-sleep-latency": 3,
-            "tickless-from-us-ticker": true
+            "deep-sleep-latency": 3
         },
         "device_has": [
             "USTICKER",
