net: sealevel: fix a code style issue about switch and case

According to the chackpatch.pl, switch and case should be
at the same indent.
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>