cpumask: use new cpumask API in drivers/infiniband/hw/ipath

Impact: cleanup

We're moving from handing around cpumask_t's to handing around struct
cpumask *'s.  cpus_*, cpumask_t and cpu_*_map are deprecated: convert
to cpumask_*, cpu_*_mask.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ralph Campbell <infinipath@qlogic.com>