Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Remove AP_KRW definition not needed after r295801.

Rename pte.h to pte-v4.h and start including directly either pte-v4.h
or pte-v6.h in files which needs it.

There are quite internal definitions in pte-v4.h and pte-v6.h headers
specific for corresponding pmap implementation. These headers should be
included only in very few files and an intention is to not hide for
which implementation such files are.

Further, sys/arm/arm/elf_trampoline.c is an example of file which
uses armv4 like pmap implementation for both armv4 and armv6 platforms.
This is another reason why pte.h which includes specific header
according to __ARM_ARCH is not created.

Remove redundant ARM_L2_ADDR_BITS and L2_ADDR_BITS definitions and
replace them by primary ones where needed.

Remove unneeded definitions after r291406. Also remove redundant and
not used L1_ADDR_BITS definition.

ARM: create new memory attribute for writethrough cacheable memory.
- add new TEX class for WT cacheable memory
- export new TEX class to kernel as VM_MEMATTR_WT attribute
- add new aliases VM_MEMATTR_WRITE_COMBINING and
VM_MEMATTR_WRITE_BACK, it's used in DRM code

Note:
Only Cortex A8 supports WT caching in HW. On rest of Cortex CPUs,
WT requests is treated as uncacheable.

Approved by: kib (mentor)

New pmap code for armv6. Disabled by default, option ARM_NEW_PMAP enables it.

This is pretty much a complete rewrite based on the existing i386 code. The
patches have been circulating for a couple years and have been looked at by
plenty of people, but I'm not putting anybody on the hook as having reviewed
this in any formal sense except myself.

After this has gotten wider testing from the user community, ARM_NEW_PMAP
will become the default and various dregs of the old pmap code will be
removed.

Submitted by: Svatopluk Kraus <onwahe@gmail.com>,
Michal Meloun <meloun@miracle.cz>