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

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

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

Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: Ib0bf475d62fd632f6eaaad2d2efbcdedc49df3b8
Reviewed-on: http://review.whamcloud.com/7296
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>