directfb: use Yocto source mirrors for SRC_URI
directfb.org has been offline for several months now, and the "official"
DirectFB repositories on GitHub haven't been touched since October and don't
contain the 1.7.x branch or tags.
So that everyone (specifically people who don't have the Yocto Project source
mirrors configured) can download DirectFB, point the SRC_URI at the Yocto
Project source mirror directly.
(From OE-Core rev:
118bdc0db8e97d0b4f094e8ede9ea490604fdc97)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
