LU-6285 ptlrpc: Get rid of cpus_* calls as deprecated

LU-6285 ptlrpc: Get rid of cpus_* calls as deprecated

Use cpumask_* equivalents instead.
Also we are no longer supposed to directly assign cpumasks as a method
of copy, need to use cpumask_copy instead.

Change-Id: I0425cd308a363e74de8d20f9a5f144fe07431f01
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: http://review.whamcloud.com/13925
Tested-by: Jenkins
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>