sara_nbiot_evk: Expose SystemCoreClock via cmsis.h

This change is necessary as updated CMSIS/RTX require the
SystemCoreClock symbol.

Author: bulislaw

targets/TARGET_ublox/TARGET_HI2110/device/hi2110.h

@@ -21,6 +21,8 @@
  extern "C" {
 #endif
 
+#include "system_hi2110.h"
+
 /******************************************************************************/
 /*                Processor and Core Peripherals                              */
 /******************************************************************************/

targets/TARGET_ublox/TARGET_HI2110/device/system_hi2110.h

@@ -22,6 +22,7 @@ extern "C" {
 #endif
 
 #include <stdint.h>
+#include <stdbool.h>
 
 
 extern uint32_t SystemCoreClock;    /*!< System Clock Frequency (Core Clock)  */