LU-2071 lprocfs: Memory leak on lustre proc access

LU-2071 lprocfs: Memory leak on lustre proc access

Make __LPROC_SEQ_FOPS to call lprocfs_single_release in release so that
the memory allocated in single_open to be freed.
Rename some of the auto-named methods to better reflect on the nature
of the underlying calls.
The previous code used to leak 32 bytes per every lustre proc file open
that uses lprocfs_..._seq_open primitive.

Change-Id: I08cc1bbb28af444f3fa5e903e38fd4a16dc4c79b
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/4150
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: wangdi <di.wang@whamcloud.com>