Remove meta-arm-iota

Feedback received that it is not acceptable to have a distro layer
inside (https://lists.yoctoproject.org/g/meta-arm/message/6

).  Removing
from meta-arm and will create a separate git repository once that code
is ready.

Change-Id: I74d1083341d90caa038c1bd8c1d53aa565d28460
Signed-off-by: Jon Mason <jon.mason@arm.com>