Squash to "mptcp: add a new sysctl checksum_enabled"

Fix a compilation error without CONFIG_SYSCTL:

  ld: net/mptcp/protocol.o: in function `__mptcp_init_sock':
  protocol.c:(.text+0x43e): undefined reference to `mptcp_is_checksum_enabled'
  ld: net/mptcp/subflow.o: in function `subflow_v6_route_req':
  subflow.c:(.text+0xa0a): undefined reference to `mptcp_is_checksum_enabled'
  ld: net/mptcp/subflow.o: in function `subflow_v4_route_req':
  subflow.c:(.text+0xabd): undefined reference to `mptcp_is_checksum_enabled'
  ld: net/mptcp/subflow.o: in function `mptcp_subflow_init_cookie_req':
  subflow.c:(.text+0xb74): undefined reference to `mptcp_is_checksum_enabled'
  ld: net/mptcp/options.o: in function `mptcp_syn_options':
  options.c:(.text+0x68a): undefined reference to `mptcp_is_checksum_enabled'

Simply moved this function outside CONFIG_SYSCTL with the other ones.

Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Acked-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>

net/mptcp/ctrl.c

@@ -41,6 +41,11 @@ unsigned int mptcp_get_add_addr_timeout(struct net *net)
 	return mptcp_get_pernet(net)->add_addr_timeout;
 }
 
+int mptcp_is_checksum_enabled(struct net *net)
+{
+	return mptcp_get_pernet(net)->checksum_enabled;
+}
+
 static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 {
 	pernet->mptcp_enabled = 1;
@@ -49,11 +54,6 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 }
 
 #ifdef CONFIG_SYSCTL
-int mptcp_is_checksum_enabled(struct net *net)
-{
-	return mptcp_get_pernet(net)->checksum_enabled;
-}
-
 static struct ctl_table mptcp_sysctl_table[] = {
 	{
 		.procname = "enabled",