LU-6245 libcfs: fix racey module handling

LU-6245 libcfs: fix racey module handling

While working on the upstream client Greg pointed out the
current why we handle libcfs module loading with psdev is
very racy. This patch removes the possible race.

Change-Id: Ic86aa9b0d426cc53a239ae81fc92db2d5a2b5c60
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: http://review.whamcloud.com/18964
Reviewed-by: Frank Zago <fzago@cray.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>