This upgrades U-Boot to 2018.11 release and drop the backported
security fixes which are now included upstream.
(From OE-Core rev: 04469ab5b7f0446404b4cb55a15595678581ab26)
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>