There is a bug in cpufreq call back funtion in timer_tsc routines,
that can result in system deadlock. The issue is: grabbing the
write_lock on xtime_lock without disabling the interrupts. So,=20
if we happen to get a timer interrupt while we are in this code,
system will go into a deadlock.

This bug only effects the kernels that have CONFIG_CPU_FREQ enabled.