ndisc: Remove unused ndisc_ifinfo_sysctl_strategy() declaration

Commit f8572d8f2a2b ("sysctl net: Remove unused binary sysctl code")
left behind this declaration.

Signed-off-by: Yue Haibing <[e-mail]>
Reviewed-by: David Ahern <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/ndisc.h

···
 #ifdef CONFIG_SYSCTL
 int ndisc_ifinfo_sysctl_change(struct ctl_table *ctl, int write,
 			       void *buffer, size_t *lenp, loff_t *ppos);
-int ndisc_ifinfo_sysctl_strategy(struct ctl_table *ctl,
-				 void __user *oldval, size_t __user *oldlenp,
-				 void __user *newval, size_t newlen);
 #endif
 
 void inet6_ifinfo_notify(int event, struct inet6_dev *idev);