Cleanup cpu/arm920t using SoC

Hi there,

Since the cpu/ directory gets clobbered with peripheral driver code I started cleaning up cpu/arm920t.
I introduced the concept of Soc (system on a chip) into the ./cpu directory. That means that code that is cpu (i.e. core) specific resides in

	cpu/$(CPU)/

and code that is specific to some SoC (i.e. vendor specific peripherals around the core) is moved into

	cpu/$(CPU)/$(SOC)/

Thus a library/archive "cpu/$(CPU)/$(SOC)/lib$(SOC).a" will be build and linked. Examples will be

	cpu/arm920t/imx/
	cpu/arm920t/s3c24x0

One can select an SoC by passing the name of it to ./mkconfig just like

	@./mkconfig $(@:_config=) arm arm920t vcma9 mpl s3c24x0

If there's no VENDOR field (like "mpl" in the above line) one has to pass NULL instead:

	@./mkconfig $(@:_config=) arm arm920t mx1ads NULL imx

=========================================================================
CHANGELOG

* Patch by Steven Scholz, 16 Aug 2004:
- Introducing the concept of SoCs "./cpu/$(CPU)/$(SOC)"
- creating subdirs for SoCs ./cpu/arm920t/imx and ./cpu/arm920t/s3c24x0
- moving SoC specific code out of cpu/arm920t/ into cpu/arm920t/$(SOC)/
- moving drivers/s3c24x0_i2c.c and drivers/serial_imx.c out of drivers/

     into cpu/arm920t/$(SOC)/

=========================================================================

Since the patch is quite big I'll send it to Wolfgang directly. If it gets applied I'd like to do the same with cpu/at91rm9200. That is introducing "SOC = at91rm9200" and moving all at91rm9200 code ./cpu/arm920t/at91rm9200.

The patch does not break the build process for ARM9. I tested "./MAKEALL ARM9"

Thanks.

Steven Scholz