[NET]: kconfig, correct traffic shaper

As Patrick McHardy <kaber@trash.net> suggested, Traffic Shaper is now
obsolete and alternative to it is no longer CBQ, since its problems with
virtual devices, alter Kconfig text to reflect this -- put a link to the
traffic schedulers as a whole.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>