net: phylink: resolve fixed link flow control

Resolve the fixed link flow control using the recently introduced
linkmode_resolve_pause() helper, which we use in
phylink_get_fixed_state() only when operating in full duplex mode.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>