cpuidle: build fix for non-x86

cpuidle: build fix for non-x86

The last posted version of this patch gave compile error
on IA64. So, here goes yet another rewrite of the patch.

Convert cpu_idle_wait() to cpuidle_kick_cpus() which is
SMP-only, and gives error on non supported CPU.

Changes from last patch sent by Kevin:
Moved the definition of kick_cpus back to cpuidle.c from cpuidle.h:
* Having it in .h gives #error on archs which includes the header file without
  actually having CPU_IDLE configured. To make it work in .h, we need one more
  #ifdef around that code which makes it messy.
* Also, the function is only called from one file. So, it can be in declared
  statically in .c rather than making it available to everyone who includes
  the .h file.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Kevin Hilman <khilman@mvista.com>
Signed-off-by: Len Brown <len.brown@intel.com>