configs: linaro-base: Set CONFIG_PROC_DEVICETREE=y

Both the Android and Ubuntu have QA tests which expect to be able to
validate device-tree booting by looking in /proc/device-tree, so we
should enable this for all Linaro builds.

At the same time we can remove this option from ubuntu.conf as it's not
an Ubuntu specific requirement.

Signed-off-by: Jon Medhurst <tixy@linaro.org>
2 files changed