[NET]: move config options out to individual protocols

Move the protocol specific config options out to the specific protocols.
With this change net/Kconfig now starts to become readable and serve as a
good basis for further re-structuring.

The menu structure is left almost intact, except that indention is
fixed in most cases. Most visible are the INET changes where several
"depends on INET" are replaced with a single ifdef INET / endif pair.

Several new files were created to accomplish this change - they are
small but serve the purpose that config options are now distributed
out where they belongs.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/xfrm/Kconfig

@@ -1,6 +1,10 @@
 #
 # XFRM configuration
 #
+config XFRM
+       bool
+       depends on NET
+
 config XFRM_USER
 	tristate "IPsec user configuration interface"
 	depends on INET && XFRM
@@ -10,3 +14,14 @@ config XFRM_USER
 
 	  If unsure, say Y.
 
+config NET_KEY
+	tristate "PF_KEY sockets"
+	select XFRM
+	---help---
+	  PF_KEYv2 socket family, compatible to KAME ones.
+	  They are required if you are going to use IPsec tools ported
+	  from KAME.
+
+	  Say Y unless you know what you are doing.
+
+