As of r257209, all architectures have defined VM_KMEM_SIZE_SCALE.  In other
words, every architecture is now auto-sizing the kmem arena.  This revision
changes kmeminit() so that the definition of VM_KMEM_SIZE_SCALE becomes
mandatory and the definition of VM_KMEM_SIZE becomes optional.

Replace or eliminate all existing definitions of VM_KMEM_SIZE.  With
auto-sizing enabled, VM_KMEM_SIZE effectively became an alternate spelling
for VM_KMEM_SIZE_MIN on most architectures.  Use VM_KMEM_SIZE_MIN for
clarity.

Change kmeminit() so that the effect of defining VM_KMEM_SIZE is similar to
that of setting the tunable vm.kmem_size.  Whereas the macros
VM_KMEM_SIZE_{MAX,MIN,SCALE} have had the same effect as the tunables
vm.kmem_size_{max,min,scale}, the effects of VM_KMEM_SIZE and vm.kmem_size
have been distinct.  In particular, whereas VM_KMEM_SIZE was overridden by
VM_KMEM_SIZE_{MAX,MIN,SCALE} and vm.kmem_size_{max,min,scale}, vm.kmem_size
was not.  Remedy this inconsistency.  Now, VM_KMEM_SIZE can be used to set
the size of the kmem arena at compile-time without that value being
overridden by auto-sizing.

Update the nearby comments to reflect the kmem submap being replaced by the
kmem arena.  Stop duplicating the auto-sizing formula in every machine-
dependent vmparam.h and place it in kmeminit() where auto-sizing takes
place.

Reviewed by:	kib (an earlier version)
Sponsored by:	EMC / Isilon Storage Division
Remove 'inline' from ar9300_init_pll(), it's too big to inline.

Submitted by:	adrian@
Add bits for the AMD features from CPUID function 0x80000001 ECX,
described in the rev. 3.0 of the Kabini BKDG, document 48751.pdf.

Partially based on the patch submitted by:	Dmitry Luhtionov <dmitryluhtionov@gmail.com>
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week