LU-8836 lprocfs: move lprocfs_stats_[un]lock to a source file

LU-8836 lprocfs: move lprocfs_stats_[un]lock to a source file

There is no reason to export lprocfs_stats_alloc_one.
The reason is due to the functions lprocfs_stats_[un]lock
being inline functions in a header file. Lets untangle
this mess and turn those inline functions into real
functions in a source file.

Change-Id: I8e33f36226c54baa93c50beb716705d20a55fa58
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/23773
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>