[SCTP]: Kill unused static inline sctp_sysctl_jiffies_ms

After the patch:
$ git-grep sctp_sysctl_jiffies_ms | wc -l
0

Signed-off-by: Ilpo Järvinen <[e-mail]>
Acked-by: Vlad Yasevich <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/sctp/sctp.h

···
 #else
 static inline void sctp_sysctl_register(void) { return; }
 static inline void sctp_sysctl_unregister(void) { return; }
-static inline int sctp_sysctl_jiffies_ms(ctl_table *table, int __user *name, int nlen,
-		void __user *oldval, size_t __user *oldlenp,
-		void __user *newval, size_t newlen) {
-	return -ENOSYS;
-}
 #endif
 
 /* Size of Supported Address Parameter for 'x' address types. */