adds various options to cifs_show_options
(displayed when you cat /proc/mounts with a cifs mount).  I limited
the new ones to values that are associated with the mount with the
exception of "seal" (which is a per tree connection property, but I
thought was important enough to show through).

Eventually cifs's parse_mount_options also needs to
be rewritten to use the match_token API but that would be a big enough
change that I would prefer that changing parse_mount_options wait
until next release.
Signed-off-by: Steve French <sfrench@us.ibm.com>