[INET_SOCK]: Move struct inet_sock & helper functions to net/inet_sock.h

To help in reducing the number of include dependencies, several files were
touched as they were getting needed headers indirectly for stuff they use.

Thanks also to Alan Menegotto for pointing out that net/dccp/proto.c had
linux/dccp.h include twice.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/udp.h b/include/linux/udp.h
index b60e0b4..85a5565 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -35,10 +35,10 @@
 #define UDP_ENCAP_ESPINUDP	2 /* draft-ietf-ipsec-udp-encaps-06 */
 
 #ifdef __KERNEL__
-
 #include <linux/config.h>
-#include <net/sock.h>
-#include <linux/ip.h>
+#include <linux/types.h>
+
+#include <net/inet_sock.h>
 
 struct udp_sock {
 	/* inet_sock has to be the first member */