Add fs_options flag to the disk_layout.json file.

The fs_options flag allows to pass command line options to the
program that format the filesystem. These options are specific to
the fs_format, so a dictionary can be speficied allowing different
default options for different filesystems.

TEST=./build_image --board=link still works.
    ` readfsoptions base disk_layout.json 3` also works.

Change-Id: Id0b1abb1637a08621a8f216619868be0e49d4e6b
Trybot-Ready: Alex Deymo <>
Tested-by: Alex Deymo <>
Reviewed-by: Mike Frysinger <>
Commit-Queue: Alex Deymo <>
3 files changed