net: switch memcpy_fromiovec()/memcpy_fromiovecend() users to copy_from_iter()

That takes care of the majority of ->sendmsg() instances - most of them
via memcpy_to_msg() or assorted getfrag() callbacks.  One place where we
still keep memcpy_fromiovecend() is tipc - there we potentially read the
same data over and over; separate patch, that...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 2c9d2520..f027a70 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -382,7 +382,7 @@
 
 	skb->transport_header = skb->network_header;
 	err = -EFAULT;
-	if (memcpy_fromiovecend((void *)iph, msg->msg_iter.iov, 0, length))
+	if (memcpy_from_msg(iph, msg, length))
 		goto error_free;
 
 	iphlen = iph->ihl * 4;