x86: Add a BSP cpu_dev helper

Add a function ptr to struct cpu_dev which is destined to be run only
once on the BSP during boot.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/20110805180116.GB26217@aftab


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>