cifs: print session id while listing open files

In the output of /proc/fs/cifs/open_files, we only print
the tree id for the tcon of each open file. It becomes
difficult to know which tcon these files belong to with
just the tree id.

This change dumps ses id in addition to all other data today.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>