Avoid TLB flush IPIs for the cores in deeper c-states by voluntary leave_mm()
before entering into that state. CPUs tend to flush TLB in those c-states
anyways.

acpi_idle does this with C3-type states, but it was not caried over
when intel_idle was introduced.  intel_idle can apply it
to C-states in addition to those that ACPI might export as C3...
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>