amd64: cpu_info: rearrange members, keep ci_mds_tmp 32-byte aligned

amd64: cpu_info: rearrange members, keep ci_mds_tmp 32-byte aligned

ci_mds_tmp needs to be 32-byte aligned, otherwise we trip a CTASSERT
in amd64/cpu.c and break kernel compilation.  However, ci_mds_tmp's
32-byte alignment is at risk: the size of schedstate_percpu is about
to change.

Move ci_curproc and ci_schedstate up just after ci_mds_buf.  This puts
ci_mds_tmp at page offset 64 with no structs ahead of it in cpu_info.
With this arrangement it should remain 32-byte aligned without much
effort.

With input from guenther@.

ok guenther@