macvlan: Replace strncpy() by strscpy()

The strncpy() function is being deprecated. Replace it by the safer
strscpy() and fix the following Coverity warning:

"Calling strncpy with a maximum size argument of 16 bytes on destination
array ifrr.ifr_ifrn.ifrn_name of size 16 bytes might leave the destination
string unterminated."

Notice that, unlike strncpy(), strscpy() always null-terminates the
destination string.

Addresses-Coverity-ID: 1445537 ("Buffer not null terminated")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/macvlan.c

@@ -831,7 +831,7 @@ static int macvlan_do_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 	struct ifreq ifrr;
 	int err = -EOPNOTSUPP;
 
-	strncpy(ifrr.ifr_name, real_dev->name, IFNAMSIZ);
+	strscpy(ifrr.ifr_name, real_dev->name, IFNAMSIZ);
 	ifrr.ifr_ifru = ifr->ifr_ifru;
 
 	switch (cmd) {