bblayers.conf: remove meta-xilinx
bblayers.conf: remove meta-xilinx

There are multiple issues with meta-xilinx, so don't include it at this time.

Signed-off-by: Trevor Woerner <8835777cd84fba3d7873eabbbe1f2de2d3f25b00@gmail.com>

twoerner/angstrom-manifest,koenkooi/angstrom-manifest,ndechesne/qcom-oe-manifest,linaro-home/lhg-oe-manifests,Angstrom-distribution/angstrom-manifest,96boards/oe-rpb-manifest