net: phylink: use phylib resolved flow control modes

Use the new phy_get_pause() helper to get the resolved pause modes for
a PHY rather than resolving the pause modes ourselves. We temporarily
retain our pause mode resolution for causes where there is no PHY
attached, e.g. for fixed-link modes.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>