LU-3319 procfs: move mdd/ofd proc handling to seq_files

LU-3319 procfs: move mdd/ofd proc handling to seq_files

With 3.10 linux kernel and above proc handling now only
uses struct seq_files. This patch migrates the mdd/ofd
layer proc entries over to using seq_files.

Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: I61b7df6bfd5efd0f12e3ca1a1813b7b62d493168
Reviewed-on: http://review.whamcloud.com/8049
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@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>