dpaa2-eth: install a single steering rule when SHARED_FS is enabled

When SHARED_FS is enabled on a DPNI object the flow steering tables are
shared between all the traffic classes. Modify the driver so that we
only add a new flow steering entry on the TC#0 when this new option is
enabled.

Signed-off-by: Ionut-robert Aron <ionut-robert.aron@nxp.com>
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>