Refactor the "platform" defitions into fdt_platform.h

Rename ARM_PLATFORM to FDT_PLATFORM and make it available outside arm.

Implement zynq_platform_reset()

Retire PARALLELLA and ZEDBOARD kernel configs.

The Zynq-7000 port has been converted to Devicetree and is supported
by the GENERIC kernel now.

Add OCM to devmap

Add AP startup for Zynq-7000.

Remove unnecessary code in zynq_platform_device_register

Merge thorpej-cfargs branch:

Simplify and make extensible the config_search() / config_found() /
config_attach() interfaces: rather than having different variants for
which arguments you want pass along, just have a single call that
takes a variadic list of tag-value arguments.

Adjust all call sites:
- Simplify wherever possible; don't pass along arguments that aren't
actually needed.
- Don't be explicit about what interface attribute is attaching if
the device only has one. (More simplification.)
- Add a config_probe() function to be used in indirect configuiration
situations, making is visibly easier to see when indirect config is
in play, and allowing for future change in semantics. (As of now,
this is just a wrapper around config_match(), but that is an
implementation detail.)

Remove unnecessary or redundant interface attributes where they're not
needed.

There are currently 5 "cfargs" defined:
- CFARG_SUBMATCH (submatch function for direct config)
- CFARG_SEARCH (search function for indirect config)
- CFARG_IATTR (interface attribte)
- CFARG_LOCATORS (locators array)
- CFARG_DEVHANDLE (devhandle_t - wraps OFW, ACPI, etc. handles)

...and a sentinel value CFARG_EOL.

Add some extra sanity checking to ensure that interface attributes
aren't ambiguous.

Use CFARG_DEVHANDLE in MI FDT, OFW, and ACPI code, and macppc and shark
ports to associate those device handles with device_t instance. This
will trickle trough to more places over time (need back-end for pre-OFW
Sun OBP; any others?).

branches: 1.4.2;
Call acpi_device_register() / fdtbus_device_register() as approrpriate.

branches: 1.3.2;
Get rid of a4x bus_space tag from fdtbus_attach_args. The only consumer
of this was various com(4) glue so modify all of that to use the new
com_init_regs_stride instead.

Add support for KASAN on ARMv[67]

Thanks to maxv for many pointers and reviews.

branches: 1.1.10;
Initial commit of FDTised Xilinx Zynq-7000 support. Tested with

qemu-system-arm -M xilinx-zynq-a9 -dtb zynq-zed.dtb -kernel netbsd.ub \
-serial /dev/null -serial stdio

Based on a set of diffs/files from rjs@

sys/arch/arm/zynq is kept in place to allow existing kernels (e.g.
ZEDBOARD and PARALLELLA) to continue to build/work during the transition,
but eventually sys/arch/arm/zynq will be deleted.