Remove tickless assert for tick count

Remove the assert that the tick count of the OS matches the tick
count of the tickless timer as this occurs frequently when
debugging. This is because the function svcRtxKernelResume
only increments the OS's tick count until the next wakeup event
so if the device was halted by a debugger past the next wakeup
event the tick counts will be out of sync.

rtos/TARGET_CORTEX/mbed_rtx_idle.cpp

@@ -194,7 +194,6 @@ static void default_idle_hook(void)
 
     core_util_critical_section_enter();
     uint32_t ticks_to_sleep = svcRtxKernelSuspend();
-    MBED_ASSERT(os_timer->get_tick() == svcRtxKernelGetTickCount());
     if (ticks_to_sleep) {
         os_timer->schedule_tick(ticks_to_sleep);