Import mbed version

from
https://github.com/ARMmbed/nrf51-sdk/blob/master/source/nordic_sdk/compo
nents/drivers_nrf/hal/nrf_nvmc.h

cores/nRF5/nRF5_SDK_11/components/drivers_nrf/hal/nrf_nvmc.h

-/* Copyright (c) 2012 Nordic Semiconductor. All Rights Reserved.
+/*
+ * Copyright (c) Nordic Semiconductor ASA
+ * All rights reserved.
  *
- * The information contained herein is confidential property of Nordic 
- * Semiconductor ASA.Terms and conditions of usage are described in detail 
- * in NORDIC SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT. 
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
  *
- * Licensees are granted free, non-transferable use of the information. NO
- * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
- * the file.
+ *   1. Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright notice, this
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+ *   other materials provided with the distribution.
+ *
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+ *   contributors to this software may be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- * $LastChangedRevision: 17685 $
  */
 
 /**