cbfstool: Use cbfs_image API for "create" command.

Usage Changes: To support platforms with different memory layout, "create" takes
two extra optional parameters:

    "-b": base address (or offset) for bootblock. When omitted, put bootblock in
          end of ROM (x86  style).
    "-H": header offset. When omitted, put header right before bootblock,
          and update a top-aligned virtual address reference in end of ROM.

  Example: (can be found in ARM MAkefile):
    cbfstool coreboot.rom create -m armv7 -s 4096K -B bootblock.bin \
             -a 64 -b 0x0000 -H 0x2040 -o 0x5000

Verified to boot on ARM (Snow) and X86 (QEMU).

Change-Id: Ida2a9e32f9a459787b577db5e6581550d9d7017b
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/2214
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/arch/armv7/Makefile.inc

@@ -45,9 +45,10 @@ prebuild-files = \
 	$(if $(call extract_nth,4,$(file)),-b $(call extract_nth,4,$(file))) &&)
 prebuilt-files = $(foreach file,$(cbfs-files), $(call extract_nth,1,$(file)))
 
+# TODO Change -b, -H, -o to Kconfig variables.
 $(obj)/coreboot.pre1: $(objcbfs)/bootblock.bin $$(prebuilt-files) $(CBFSTOOL)
 	$(CBFSTOOL) $@.tmp create -m armv7 -s $(CONFIG_COREBOOT_ROMSIZE_KB)K \
-		-B $(objcbfs)/bootblock.bin -a 64
+		-B $(objcbfs)/bootblock.bin -a 64 -b 0x0000 -H 0x2040 -o 0x5000
 	$(prebuild-files) true
 	mv $@.tmp $@
 else