[UDP]: Revert udplite and code split.

This reverts commit db1ed684f6 ("[IPV6]
UDP: Rename IPv6 UDP files."), commit
8be8af8fa4 ("[IPV4] UDP: Move
IPv4-specific bits to other file.") and commit
e898d4db27 ("[UDP]: Allow users to
configure UDP-Lite.").

First, udplite is of such small cost, and it is a core protocol just
like TCP and normal UDP are.

We spent enormous amounts of effort to make udplite share as much code
with core UDP as possible.  All of that work is less valuable if we're
just going to slap a config option on udplite support.

It is also causing build failures, as reported on linux-next, showing
that the changeset was not tested very well.  In fact, this is the
second build failure resulting from the udplite change.

Finally, the config options provided was a bool, instead of a modular
option.  Meaning the udplite code does not even get build tested
by allmodconfig builds, and furthermore the user is not presented
with a reasonable modular build option which is particularly needed
by distribution vendors.

Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -1317,18 +1317,15 @@ static int __init init_ipv4_mibs(void)
 	if (snmp_mib_init((void **)udp_statistics,
 			  sizeof(struct udp_mib)) < 0)
 		goto err_udp_mib;
-#ifdef CONFIG_IP_UDPLITE
 	if (snmp_mib_init((void **)udplite_statistics,
 			  sizeof(struct udp_mib)) < 0)
 		goto err_udplite_mib;
-#endif
+
 	tcp_mib_init();
 
 	return 0;
 
-#ifdef CONFIG_IP_UDPLITE
 err_udplite_mib:
-#endif
 	snmp_mib_free((void **)udp_statistics);
 err_udp_mib:
 	snmp_mib_free((void **)tcp_statistics);
@@ -1426,10 +1423,8 @@ static int __init inet_init(void)
 	/* Setup UDP memory threshold */
 	udp_init();
 
-#ifdef CONFIG_IP_UDPLITE
 	/* Add UDP-Lite (RFC 3828) */
 	udplite4_register();
-#endif
 
 	/*
 	 *	Set the ICMP layer up