dpaa_eth: fix pause capability advertisement logic

The ADVERTISED_Asym_Pause bit was being improperly set when both
rx and tx pause were enabled. When rx and tx are both enabled, only
the ADVERTISED_Pause bit is supposed to be set.

Signed-off-by: Jake Moroni <mail@jakemoroni.com>
Acked-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>