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

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

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

Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: I3dbd102922060576cb57495da73e6d93c117c2e3
Reviewed-on: http://review.whamcloud.com/7139
Reviewed-by: Peng Tao <bergwolf@gmail.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>