[NET]: add a top-level Networking menu to *config

Create a new top-level menu named "Networking" thus moving
net related options and protocol selection way from the drivers
menu and up on the top-level where they belong.

To implement this all architectures has to source "net/Kconfig" before
drivers/*/Kconfig in their Kconfig file. This change has been
implemented for all architectures.

Device drivers for ordinary NIC's are still to be found
in the Device Drivers section, but Bluetooth, IrDA and ax25
are located with their corresponding menu entries under the new
networking menu item.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index d09437b..4b83261 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -515,6 +515,8 @@
 
 endmenu
 
+source "net/Kconfig"
+
 source drivers/Kconfig
 
 source "drivers/firmware/Kconfig"