net: phylink: support validated pause and autoneg in fixed-link

In fixed-link setup phylink_parse_fixedlink() unconditionally sets
Pause, Asym_Pause and Autoneg bits to "supported" bitmap, while MAC may
not support these.

This leads to ethtool reporting:

 > Supported pause frame use: Symmetric Receive-only
 > Supports auto-negotiation: Yes

regardless of what is actually supported.

Instead of unconditionally set Pause, Asym_Pause and Autoneg it is
sensible to set them according to validated "supported" bitmap, i.e. the
result of phylink_validate().

Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>