LU-3319 procfs: move FLD proc handling over to seq_file

LU-3319 procfs: move FLD proc handling over to seq_file

In order to support 3.10+ kernels for clients we adapt
the FLD proc handling to using seq_files.

Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: I056d4dcc15b82263880949a0928fc04bd6b2f0b7
Reviewed-on: http://review.whamcloud.com/7140
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Yang Sheng <yang.sheng@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>