x86, cpu: Export AMD errata definitions

Exprot the AMD errata definitions, since they are needed by kvm_amd.ko
if that is built as a module.  Doing "make allmodconfig" during
testing would have caught this.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Hans Rosenfeld <hans.rosenfeld@amd.com>
LKML-Reference: <1280336972-865982-1-git-send-email-hans.rosenfeld@amd.com>