net/ipv6/datagram.c: Checkpatch cleanups

datagram.c:101: ERROR: "(foo*)" should be "(foo *)"
datagram.c:521: ERROR: space required before the open parenthesis '('
datagram.c:830: WARNING: braces {} are not necessary for single statement blocks
datagram.c:849: WARNING: braces {} are not necessary for single statement blocks

Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
Signed-off-by: David S. Miller <davem@davemloft.net>