ipv6: Reduce switch/case indent

Make the case labels the same indent as the switch.

git diff -w shows 80 column reflowing,
removal of a useless break after return, and moving
open brace after case instead of separate line.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>