bblayers.conf: remove meta-backport
bblayers.conf: remove meta-backport

We removed meta-backport from the manifest for the master branch, and it needs
to be removed from bblayer.conf as well.

Change-Id: Ic7210891add5f8ca9f8d88f72b7bb9400020b181
Signed-off-by: Nicolas Dechesne <05fca36dfcf68f7e1c9eaf62b074676ab50a133b@linaro.org>

ndechesne/qcom-oe-manifest,96boards/oe-rpb-manifest