yaffs2utils: new package

[Thomas: remove target variant of the package, use labelled version
0.2.9 instead of latest.tar.gz, use 'make install' instead of doing
manual installation, add license informations.]

Signed-off-by: Will Wagner <willw@carallon.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>