amd64 pmap: preset A and M bits for pmap_qenter() mappings

[kib]

Summary

This removes one or two atomic update of the pte on access. Also it
makes the pte constant during its lifecycle.

[alc]

sys/amd64/amd64/pmap.c

3900–3901

Here too?

3912–3913

Here too?

P.S. If you decide to update pmap_kenter{,_attr}(), please pick one ordering for the flags and use it consistently.

[kib]

Handle kenter. Unify pte bits order in kenter/qenter.

[alc]

As an aside, I just verified that arm64 is already setting the equivalent bits.