ipv6 addrconf: revert /proc/net/if_inet6 ifa_flag format

Turned out that applications like ifconfig do not handle the change.
So revert ifa_flag format back to 2-letter hex value.

Introduced by:
commit 479840ffdbe4242e8a25349218c8e0859223aa35
"ipv6 addrconf: extend ifa_flags to u32"

Reported-by: Alexander Aring <[e-mail]>
Signed-off-by: Jiri Pirko <[e-mail]>
Tested-by: FLorent Fourcot <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv6/addrconf.c

···
 static int if6_seq_show(struct seq_file *seq, void *v)
 {
 	struct inet6_ifaddr *ifp = (struct inet6_ifaddr *)v;
-	seq_printf(seq, "%pi6 %02x %02x %02x %03x %8s\n",
+	seq_printf(seq, "%pi6 %02x %02x %02x %02x %8s\n",
 		   &ifp->addr,
 		   ifp->idev->dev->ifindex,
 		   ifp->prefix_len,
 		   ifp->scope,
-		   ifp->flags,
+		   (u8) ifp->flags,
 		   ifp->idev->dev->name);
 	return 0;
 }