net: ipv6: Standardize prefixes for message logging

Add #define pr_fmt(fmt) as appropriate.

Add "IPv6: " to appropriate files.

Convert printk(KERN_<LEVEL> to pr_<level> (but not KERN_DEBUG).
Standardize on "%s: " not "%s(): " when emitting __func__.
Use "%s: ", __func__ instead of embedding function name.
Coalesce formats, align arguments.

ADDRCONF output is now prefixed with "IPv6: "

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index ba936e1..b15dc08 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -1350,7 +1350,7 @@
 		goto reg_notif_fail;
 #ifdef CONFIG_IPV6_PIMSM_V2
 	if (inet6_add_protocol(&pim6_protocol, IPPROTO_PIM) < 0) {
-		printk(KERN_ERR "ip6_mr_init: can't add PIM protocol\n");
+		pr_err("%s: can't add PIM protocol\n", __func__);
 		err = -EAGAIN;
 		goto add_proto_fail;
 	}