Merge pull request #5598 from bulislaw/remove_rtx_int_header

Remove unnecessary inclusion of an internal RTX header

Author: 0xc0170

rtos/TARGET_CORTEX/mbed_rtx_idle.cpp

@@ -24,7 +24,6 @@
 #include "platform/mbed_sleep.h"
 #include "TimerEvent.h"
 #include "lp_ticker_api.h"
-#include "rtx_core_cm.h"
 #include "mbed_critical.h"
 #include "mbed_assert.h"
 #include <new>