net: Kill ratelimit.h dependency in linux/net.h

Ingo Molnar noticed that we have this unnecessary ratelimit.h
dependency in linux/net.h, which hid compilation problems from
people doing builds only with CONFIG_NET enabled.

Move this stuff out to a seperate net/net_ratelimit.h file and
include that in the only two places where this thing is needed.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/net/net_ratelimit.h b/include/net/net_ratelimit.h
new file mode 100644
index 0000000..7727b42
--- /dev/null
+++ b/include/net/net_ratelimit.h
@@ -0,0 +1,8 @@
+#ifndef _LINUX_NET_RATELIMIT_H
+#define _LINUX_NET_RATELIMIT_H
+
+#include <linux/ratelimit.h>
+
+extern struct ratelimit_state net_ratelimit_state;
+
+#endif	/* _LINUX_NET_RATELIMIT_H */