Merge forward from matt-nb5-mips64.

branches: 1.7.4; 1.7.6; 1.7.8;
Use a common version of cpu.c (mmm removing identical code).

branches: 1.6.10; 1.6.28;
Since files.wscons et al. are included by ~all ports anyway, include
them in the mi "files" file, and remove include statements from md files.
These shouldn't pull in additional kernel code when not in use, so it
shouldn't do any harm except a risk of namespace collisions which
should be easy to fix.

branches: 1.5.2; 1.5.32;
Various improvements to make the common mips3 clock handling more generally
useful. The functions delay, cpu_initclocks, and setstatclcokrate have been
renamed to mips3_delay, mips3_initclocks, and mips3_setstatclockrate.

We provide weak aliases for the original names, so machdep code doesn't have
to provide wrapper routines. (Giving good performance.)

I've moved mips3_clockintr, mips3_initclocks, and mips3_setstatclockrate to
their own mips3_clockintr file, because some ports may not be able to use
these, and its senseless to carry that baggage.

branches: 1.4.2;
Use new common, MIPS3 clock handling. This eliminates some port-specific
code in favor of common MIPS3 code.

branches: 1.3.4;
Add support for AR5312 on-chip watchdog.
While we're here, fix mainbus so that mainbus doesn't complain about
unconfigured devices, and use the *atheros* mainbus instead of alchemy (doh!)

branches: 1.2.2; 1.2.4; 1.2.6; 1.2.8; 1.2.10;
Rework evbmips clock architecture to use common clock_subr.h routines.

Additionally, do not fail if no RTC is present, as not all boards have one.

Malta now uses the common dev/ic/mc146818.c code as much as possible, reducing
local "custom" code. These malta changes are *untested*, as I do not have
a Malta board to test with. If someone would please test them and get back to
me, I'd appreciate it!

Initial import of Atheros AR531X SoC support. Currently the onboard ethernet
and serial ports are supported, and the system appears stable with an NFS
mounted root. An earlier version of the code was reviewed by simon@, but it
has since had numerous improvements and cleanups.


At the moment, only AR5312 is known to work, but I suspect AR2313 will work
as well. Later 2315/2316 parts are substantially different, and are not yet
supported. Wifi and Marvell switch support found on some designs are not yet
supported.

Platforms known to include AR5312 include Senao Aries 2 (AP5054) and Netgear
WGU624.