smb: client: stop revalidating reparse points unnecessarily

Query dir responses don't provide enough information on reparse points
such as major/minor numbers and symlink targets other than reparse
tags, however we don't need to unconditionally revalidate them only
because they are reparse points.  Instead, revalidate them only when
their ctime or reparse tag has changed.

For instance, Windows Server updates ctime of reparse points when
their data have changed.

Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>