cbfstool: Use cbfs_image API for "extract" command.

Change the "extract" command to use cbfs_export_entry API. Nothing changed in
its usage.

To verify, run "cbfstool coreboot.rom extract -f blah -n blah" and check if the
raw type file is correctly extracted.

Change-Id: I1ed280d47a2224a9d1213709f6b459b403ce5055
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/2207
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
3 files changed