PR/49422: Ryo ONODERA: patch(1) cannot handle context diffs
Revert sys/arch/x86/x86/pmap.c 1.185; a CPU needs to get pmap updates,
especially for pmap_kernel(), as soon as it is up.
Instead move all pmap-related cpu_info initialisations, including
initializing ci_kpm_mtx, in cpu_attach_common() from cpu_init()
(ci_pmap and ci_tlbstate as already initialized in cpu_attach_common()).