smp_call_function() only lets all other CPUs execute a specific function,

smp_call_function() only lets all other CPUs execute a specific function,
while we expect all CPUs do in intel_idle.  Without the fix, we could have
one cpu which has auto_demotion enabled or has no boradcast timer setup.
Usually we don't see impact because auto demotion just harms power and the
intel_idle init is called in CPU 0, where boradcast timer delivers
interrupt, but this still could be a problem.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>