cifs: Add witness information to debug data dump

+ Indicate if witness feature is supported
+ Indicate if witness is used when dumping tcons
+ Dumps witness registrations. Example:
  Witness registrations:
  Id: 1 Refs: 1 Network name: 'fs.fover.ad'(y) Share name: 'share1'(y) \
    Ip address: 192.168.103.200(n)

Signed-off-by: Samuel Cabrero <scabrero@suse.de>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>