staging: lustre: remove cfs_for_each_possible_cpu()

It was just a wrapper around for_each_possible_cpu()

Cc: Peng Tao <tao.peng@emc.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>