LU-56 ptlrpc: CPT affinity ptlrpc RS handlers

LU-56 ptlrpc: CPT affinity ptlrpc RS handlers

This patch covered a couple of things:
- reimplement RS handler by using CPU partition APIs
- Instead of always round-robin choose RS handler thread, this patch
  directly choose RS handler thread on partition of rs::rs_svcpt

Signed-off-by: Liang Zhen <liang@whamcloud.com>
Change-Id: I5fdebb116630d073d41b39fc4271c4cebb429965
Reviewed-on: http://review.whamcloud.com/3135
Reviewed-by: wangdi <di.wang@whamcloud.com>
Tested-by: Hudson
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>