Remove all old-style cpumask operators, and cpumask_t.

Also: get rid of the unused define_siblings function.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Mark Langsdorf <mark.langsdorf@amd.com>
Tested-by: Mark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: Dave Jones <davej@redhat.com>