Move #ifdef around function definiton into the function and
unconditionally return on X86_32.  Saves an ifdef from the
one callsite.

[ mingo@elte.hu: minor cleanup. ]
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>