Provide a shared pmap_devmap implementation and convert all pmap_devmap
arrays to use DEVMAP_ENTRY{,_END}

Rename VM_KERNEL_IO_ADDRESS to VM_KERNEL_IO_BASE to match RISC-V

It's less letters, matches other similar variables and will help with
sharing code between the two architectures.

NFCI.

Use CACHE_LINE_SIZE instead of magic number 128.

aarch64: curcpu() audit.

Sprinkle KASSERT (or KDASSERT in hot paths) for kpreempt_disabled()
when we use curcpu() and it's not immediately obvious that the caller
has preemption disabled but closer scrutiny suggests the caller has.

Note unsafe curcpu()s for syscall event counting. Not sure this is
worth changing.

Possible bugs fixed:

- cpu_irq and cpu_fiq could be preempted while trying to run softints
on this CPU.

- data_abort_handler might incorrectly think it was invoked in
interrupt context when it was only preempted and migrated to
another CPU.

- pmap_fault_fixup might report the wrong CPU logs.

(However, we don't currently run with kpreemption on aarch64, so
these are not yet real bugs fixed except if you patch it to build
with __HAVE_PREEMPTION.)

Rename pmap_md_pdetab_destroy to pmap_md_pdetab_fini to match
pmap_md_pdetab_init.

Call pmap_md_pdetab_fini from pmap_segtab_destroy.

Provide MI PMAP support on AARCH64

aarch64: curcpu() audit.

Sprinkle KASSERT (or KDASSERT in hot paths) for kpreempt_disabled()
when we use curcpu() and it's not immediately obvious that the caller
has preemption disabled but closer scrutiny suggests the caller has.

Note unsafe curcpu()s for syscall event counting. Not sure this is
worth changing.

Possible bugs fixed:

- cpu_irq and cpu_fiq could be preempted while trying to run softints
on this CPU.

- data_abort_handler might incorrectly think it was invoked in
interrupt context when it was only preempted and migrated to
another CPU.

- pmap_fault_fixup might report the wrong CPU logs.

(However, we don't currently run with kpreemption on aarch64, so
these are not yet real bugs fixed except if you patch it to build
with __HAVE_PREEMPTION.)

Rename pmap_md_pdetab_destroy to pmap_md_pdetab_fini to match
pmap_md_pdetab_init.

Call pmap_md_pdetab_fini from pmap_segtab_destroy.

Provide MI PMAP support on AARCH64

Rename pmap_md_pdetab_destroy to pmap_md_pdetab_fini to match
pmap_md_pdetab_init.

Call pmap_md_pdetab_fini from pmap_segtab_destroy.

Provide MI PMAP support on AARCH64