sched: Do not support colocation on cluster with one CPU

Add check to make sure we do not colocate tasks to cluster
which has only one CPU. If tasks in a group should migrate,
tasks shouldn't migrate to cluster with only one CPU as CPU
won't be able to handle all the tasks in the group.

Change-Id: I01fdc9cf625eeaa01e2c4f137edb21e8610d41c1
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>