Beetle: Implement sleep API

Author: bulislaw

hal/targets.json

@@ -1640,7 +1640,7 @@
                 "template": ["uvision5_arm_beetle_soc.uvproj.tmpl"]
             }
         },
-        "device_has": ["ANALOGIN", "CLCD", "I2C", "INTERRUPTIN", "LOWPOWERTIMER", "PORTIN", "PORTINOUT", "PORTOUT", "SERIAL", "SPI"],
+        "device_has": ["ANALOGIN", "CLCD", "I2C", "INTERRUPTIN", "LOWPOWERTIMER", "PORTIN", "PORTINOUT", "PORTOUT", "SERIAL", "SLEEP", "SPI"],
         "features": ["BLE"],
         "release_versions": ["2", "5"]
     },

hal/targets/hal/TARGET_ARM_SSG/TARGET_BEETLE/sleep.c

@@ -0,0 +1,29 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2016 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "sleep_api.h"
+#include "cmsis.h"
+
+ void sleep(void)
+ {
+    SystemPowerSuspend(POWER_MODE_SLEEP);
+    SystemPowerResume(POWER_MODE_SLEEP);
+ }
+
+void deepsleep(void)
+{
+    SystemPowerSuspend(POWER_MODE_DEEP_SLEEP);
+    SystemPowerResume(POWER_MODE_DEEP_SLEEP);
+}