LU-2158 lvfs: Remove functions from lvfs_linux.c

LU-2158 lvfs: Remove functions from lvfs_linux.c

The following functions were removed from the lvfs_linux.c file as they
are no longer used:

 * simple_mknod
 * lustre_fread
 * lustre_fwrite
 * lustre_fsync
 * l_filldir
 * l_readdir
 * l_notify_change
 * simple_truncate
 * lvfs_check_io_health

Change-Id: I6684815c85e87974277295e6906fd6d7c8dfe1be
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Christopher J. Morrone <morrone2@llnl.gov>
Reviewed-on: http://review.whamcloud.com/4859
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>