net: sealevel: open brace '{' following struct go on the same line

Fix the checkpatch error as open brace '{' following struct should
go on the same line.

Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>