LU-2158 lvfs: Remove cruft from lvfs_linux.h

LU-2158 lvfs: Remove cruft from lvfs_linux.h

Various bits from the lvfs_linux.h file were removed as they are no
longer used. Specifically, the following was removed:

 * l_inode
 * lvfs_sbdev_sync
 * lvfs_set_rdonly
 * lvfs_clear_rdonly
 * lvfs_dentry_params

Change-Id: I993a1416bb548746ca717904a483c0cd6245768e
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Reviewed-on: http://review.whamcloud.com/4862
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>