mlxsw: spectrum_acl: Move rehash_dis trace call and err msg to vregion_migrate()

Move the call of rehash_dis trace and the error message to
vregion_migrate() next to the failed_rollback flag set.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>