Handle cpumask in raw driver for unified hierarchy.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Grab a new spec.Cpu while updating masks if cpu root didn't exist.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Merge pull request #117 from rjnagal/cpumask

Handle cpumask in raw driver for unified hierarchy.