x86: merge thread_info.h

Simple merge of both thread_info_32.h and thread_info_64.h into thread_info.h.

Comments for #ifndef __ASM_THREAD_INFO_H and #ifdef __KERNEL__
are the same.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>