[NET]: Kconfig: NETCONSOLE and NETPOLL together

Put NETCONSOLE and NETPOLL options together since they are related.
This cuts down on the hassle of flipping back and forth between
the Networking menu and the Network drivers menu to change their
config settings.

Tested with menuconfig, gconfig, and xconfig.
gconfig has a small problem with this.  I think that it's
a bug in gconfig and I will take it up with Romain Lievin.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: David S. Miller <davem@davemloft.net>