doc: delete README.ARM-SoC

This document is too old and useless.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

doc/README.ARM-SoC

-[By Steven Scholz <steven.scholz@imc-berlin.de>, 16 Aug 2004]
-
-Since the cpu/ directory gets clobbered with peripheral driver code I
-started cleaning up arch/arm/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
-
-	$(CPUDIR)/
-
-and code that is specific to some SoC (i.e. vendor specific
-peripherals around the core) is moved into
-
-	$(CPUDIR)/$(SOC)/
-
-Thus a library/archive "$(CPUDIR)/$(SOC)/lib$(SOC).a" will be build
-and linked. Examples will be
-
-	arch/arm/cpu/arm920t/imx/
-	arch/arm/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