cifs: Add support for mounting Windows 2008 DFS shares
Windows 2008 CIFS servers do not always return PATH_NOT_COVERED when
attempting to access a DFS share. Therefore, when checking for remote
shares, unconditionally ask for a DFS referral for the UNC (w/out prepath)
before continuing with previous behavior of attempting to access the UNC +
prepath and checking for PATH_NOT_COVERED.
Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Sean Finney <seanius@seanius.net> Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru> Signed-off-by: Steve French <sfrench@us.ibm.com>