qede: Don't override priv_flags

Driver is now setting the ndev's priv_flags instead of adding to it,
causing pktgen failure to utilize various features due to the loss
of the IFF_TX_SKB_SHARING indication.

Fixes: 7b7e70f9 ("qed*: Allow unicast filtering")
Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>