STM32L1 assert in SetSysClock replaced

targets/TARGET_STM/TARGET_STM32L1/TARGET_NUCLEO_L152RE/device/system_clock.c

@@ -29,7 +29,7 @@
   */
 
 #include "stm32l1xx.h"
-#include "mbed_assert.h"
+#include "mbed_error.h"
 
 /*!< Uncomment the following line if you need to relocate your vector Table in
      Internal SRAM. */
@@ -114,8 +114,8 @@ void SetSysClock(void)
             if (SetSysClock_PLL_HSI() == 0)
 #endif
             {
-                while(1) {
-                    MBED_ASSERT(1);
+                {
+                    error("SetSysClock failed\n");
                 }
             }
         }