LU-3319 procfs: move configuration layer proc handling over to seq_file

LU-3319 procfs: move configuration layer proc handling over to seq_file

Various Lustre layers have a configuration abstraction for logs
which implements a proc interface. For 3.10+ kernel support we
adapt this proc handling to using seq_files.

Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: Ie507fd88cdf5193624991f7ab32bdc213a44aebc
Reviewed-on: http://review.whamcloud.com/7295
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>