LU-6285 ptlrpc: Do not recalculate siblings of CPU 0 in a loop

LU-6285 ptlrpc: Do not recalculate siblings of CPU 0 in a loop

ptlrpc_hr_init seems to be recalculating number of siblings of CPU0
in a loop which is wasteful. Just precalculate the value before the
loop and use it in every iteration instead.

Change-Id: I807fddf29a75af4d268829e37dc91b7512cfcc50
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: http://review.whamcloud.com/13905
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>