net: phylink: re-split __phylink_connect_phy()

In order to support Clause 45 PHYs on SFP+ modules, which have an
indeterminant phy interface mode, we need to be able to call
phylink_bringup_phy() with a different interface mode to that used when
binding the PHY. Reduce __phylink_connect_phy() to an attach operation,
and move the call to phylink_bringup_phy() to its call sites.

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