Add support to get layout from fmap (e.g. coreboot rom)

Flashmap, or simply fmap, is a binary data format for describing
region offsets, sizes, and certain attributes and is widely used by
coreboot. This patch adds support for the fmap data format version 1.1
and adds --fmap and --fmap-file arguments.

Using --fmap will make flashrom to search the ROM content for fmap
data. Using --fmap-file will make flashrom search a supplied file
for fmap data.

An example of how to update the COREBOOT region of a ROM:
flashrom -p programmer --fmap -w coreboot.rom -i COREBOOT
flashrom -p programmer --fmap-file coreboot.rom -w coreboot.rom -i COREBOOT

The fmap functions are mostly copied from cbfstool.

Currently it is made mutually exclusive with other layout options until
we are more clever about this input.

Change-Id: I0e7fad38ed79a84d41358e1f175c36d255786c12
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: David Hendricks <dhendricks@fb.com>
Reviewed-on: https://review.coreboot.org/23203
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Tested-by: David Hendricks <david.hendricks@gmail.com>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>

Makefile

@@ -536,7 +536,7 @@ CHIP_OBJS = jedec.o stm50.o w39.o w29ee011.o \
 ###############################################################################
 # Library code.
 
-LIB_OBJS = libflashrom.o layout.o flashrom.o udelay.o programmer.o helpers.o ich_descriptors.o
+LIB_OBJS = libflashrom.o layout.o flashrom.o udelay.o programmer.o helpers.o ich_descriptors.o fmap.o
 
 ###############################################################################
 # Frontend related stuff.