arm64 pmap: batch chunk removal in pmap_remove_pages

As with amd64 batch chunk removal in pmap_remove_pages to move it out
of the pv list lock. This is one of the main contested locks when
running poudriere on a 160 core Ampere Altra server.

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D36305