Revert "Add meta-iot-cloud layer to yocto"

This reverts commit 753edc9b, removing meta-iot-cloud from the list of layers pulled into the Yocoto sources directory. Do not merge this commit until you've merged the associated commits for bsp-base (which removes meta-iot-cloud from the bblayers file) and meta-vesta (which reverts commits that added meta-iot-cloud related bbappend files), or the automatic build triggered by this commit will fail.