Add package for rtl8168 firmware which is required by Realtek
Ethernet Controller.
(From OE-Core rev: e5315d5d820cb1b164c75a0cab3804f6c69b5ba9)
Signed-off-by: Liwei Song <liwei.song@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>