site: move from meta-oe to meta-networking

The site information only provides data for rp-pppoe which already moved
to meta-networking. Also move these files to meta-networking.

Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>