switchdev: Put export declaration in the right place

Move exporting of switchdev_port_same_parent_id to be right
below it and not elsewhere.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reported-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>