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

- Complete breaking out the definition of bus_space_{tag,handle}_t by
moving the typedef of bus_space_tag_t from sys/sparc64/include/bus.h
to sys/sparc64/include/_bus.h. This brings sparc64 in sync with the
other platforms and fixes the compilation of drivers which include
<sys/rman.h> before <machine/bus.h> after sys/sys/rman.h rev. 1.34.
- Remove the definition of bus_type_t from sys/sparc64/include/_bus.h
as it's unused since sys/sparc64/include/bus.h rev. 1.6 and
sys/sparc64/sparc64/bus_machdep.c rev. 1.3.
- Remove some pointless comments.

Break out the definition of bus_space_{tag,handle}_t and a few other types
into _bus.h to help with name space polution from including all of bus.h.
In a few days, I'll commit changes to the MI code to take advantage of thse
sepration (after I've made sure that these changes don't break anything in
the main tree, I've tested in my trees, but you never know...).

Suggested by: bde (in 2002 or 2003 I think)
Reviewed in principle by: jhb