Add option to read ROM layout from IFD

Add an option --ifd to read the ROM layout from an Intel Firmware
Descriptor (IFD). Works the same as the -l option, if given, -i
specifies the images to update.

v2: o Rebased on libflashrom, use libflashrom interface.
    o Use functions from ich_descriptors.c.

v3: o Move ich_descriptors.o to LIB_OBJS, thus build it independent
      of arch and programmers.
    o Bail out if we aren't compiled for little endian.
    o Update flashrom.8.tmpl.

v4: o Incorporated David's comments.
    o Removed single-character `-d` option.

v5: Changed region names to match the output of `ifdtool --layout ...`

Change-Id: Ifafff2bf6d5c5e62283416b3269723f81fdc0fa3
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/17953
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

Makefile

@@ -519,7 +519,7 @@ 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
+LIB_OBJS = libflashrom.o layout.o flashrom.o udelay.o programmer.o helpers.o ich_descriptors.o
 
 ###############################################################################
 # Frontend related stuff.
@@ -731,7 +731,7 @@ FEATURE_CFLAGS += -D'CONFIG_INTERNAL=1'
 PROGRAMMER_OBJS += processor_enable.o chipset_enable.o board_enable.o cbtable.o internal.o
 ifeq ($(ARCH), x86)
 PROGRAMMER_OBJS += it87spi.o it85spi.o sb600spi.o amd_imc.o wbsio_spi.o mcp6x_spi.o
-PROGRAMMER_OBJS += ichspi.o ich_descriptors.o dmi.o
+PROGRAMMER_OBJS += ichspi.o dmi.o
 ifeq ($(CONFIG_INTERNAL_DMI), yes)
 FEATURE_CFLAGS += -D'CONFIG_INTERNAL_DMI=1'
 endif