dpaa2-switch: move the dpaa2_switch_fdb_set_egress_flood function

In order to avoid a forward declaration in the next patches, move the
dpaa2_switch_fdb_set_egress_flood() function to the top of the file.

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