MAINTAINERS: Add some missing defconfig files to existing entries

We have a few places where defconfigs were added (or renamed) and not
included in their previously listed MAINTAINERS entry, correct this.

Signed-off-by: Tom Rini <trini@konsulko.com>
Acked-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>