Remove meta-arm-integration

Remove meta-arm-integration, as it is not currently being used.  Also,
remove the reference in the README.md.  These can be added bach when
they are in use again.

Change-Id: If8535d6d9a0a307a42b24e8f42e0eb7847e047c4
Signed-off-by: Jon Mason <jon.mason@arm.com>