cbfstool: Add update-fit command

Add support for filling in the Firmware Interface Table.
For now it only supports adding microcode entries.

It takes 2 options:
1. Name of file in cbfs where the mircocode is located
2. The number of empty entries in the table.

Verified with go firmware tools. Also commented out updating
microcode in the bootblock. When romstage runs, the CPUs indicate
their microcode is already loaded.

Change-Id: Iaccaa9c226ee24868a5f4c0ba79729015d15bbef
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/2712
Reviewed-by: Aaron Durbin <adurbin@google.com>
Tested-by: build bot (Jenkins)

util/cbfstool/Makefile.inc

@@ -5,6 +5,7 @@ cbfsobj += compress.o
 cbfsobj += cbfs_image.o
 cbfsobj += cbfs-mkstage.o
 cbfsobj += cbfs-mkpayload.o
+cbfsobj += fit.o
 # LZMA
 cbfsobj += lzma.o
 cbfsobj += LzFind.o