phy: unmask link partner capabilities

Masking the link partner's capabilities with local capabilities can be
misleading in autonegotiation scenarios such as PAUSE frame
autonegotiation.
This patch calculates the join between the local capabilities and the
link parner capabilities, when it determines the speed and duplex
settings, but does not mask any of the link partner capabilities when
it calculates PAUSE frame settings.

Signed-off-by: Cristian Bercaru <cristian.bercaru@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>