Simplify regmap initialization, and fix an regmap issue that
affected TI OMAP (LCR register would get clobbered due to
using the wrong offset for the MDR1 register) reported by Lwazi Dube
(who also found the root cause).

Remove the COM_REGMAP option -- just use it all the time. While here,
garbage-collect the COM_FUNCMAP and COM_AU1X00 options, as there are
not used anywhere.

Clean up initialization of com_regs structure, in preparation for
some additional changers.

branches: 1.6.52;
#include <sys/bus.h> instead of <machine/bus.h>.

Split device_t and softc for all com(4) devices (well, everything that
uses a com_softc backend). Use proper types and ansify where appropriate.

branches: 1.4.12; 1.4.16;
Merge the ppcoea-renovation branch to HEAD.

This branch was a major cleanup and rototill of many of the various OEA
cpu based PPC ports that focused on sharing as much code as possible
between the various ports to eliminate near-identical copies of files in
every tree. Additionally there is a new PIC system that unifies the
interface to interrupt code for all different OEA ppc arches. The work
for this branch was done by a variety of people, too long to list here.

TODO:
bebox still needs work to complete the transition to -renovation.
ofppc still needs a bunch of work, which I will be looking at.
ev64260 still needs to be renovated
amigappc was not attempted.

NOTES:
pmppc was removed as an arch, and moved to a evbppc target.

branches: 1.3.10;
Now that curcpu() is defined in terms of curlwp() for mips, we need to
include <sys/lwp.h> where curcpu() is used.

branches: 1.2.4; 1.2.8; 1.2.14; 1.2.20; 1.2.22; 1.2.28;
Add an option COM_REGMAP to allow com(4) to use an array of register indices.
This allows us to convert aucom to just another com attachment, and cleanup
some code in the com_arbus.c.

Additionally, we use a common com_cleanup routine rather than having a
zillion copies of it in the attachment points.

This has been tested on a number architectures, and it has been shown to get
close to comparable performance when COM_REGMAP is defined, and comparable
when it is not defined.

Approved by core@. Fixes PR port-evbmips/32362.

branches: 1.1.2;
file com_aubus.c was initially added on branch gdamore-uart.