x86, cpu: Clean up and unify the NOP selection infrastructure

x86, cpu: Clean up and unify the NOP selection infrastructure

Clean up and unify the NOP selection infrastructure:

- Make the atomic 5-byte NOP a part of the selection system.
- Pick NOPs once during early boot and then be done with it.

Signed-off-by: H. Peter Anvin <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jason Baron <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]