cbfstool: factor out parsing compression file attributes

cbfstool extract also needs it.

Change-Id: I8302bb18c5f797eb0a43ec4e4269790f3d49a896
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/11361
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed