net: fix compile error due to double return type in SOCK_DEBUG

Fix this one:
include/net/sock.h: error: two or more data types in declaration specifiers
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -74,7 +74,7 @@
 					printk(KERN_DEBUG msg); } while (0)
 #else
 /* Validate arguments and do nothing */
-static void inline int __attribute__ ((format (printf, 2, 3)))
+static inline void __attribute__ ((format (printf, 2, 3)))
 SOCK_DEBUG(struct sock *sk, const char *msg, ...)
 {
 }