net: phylink: rename phylink_sfp_config()

phylink_sfp_config() now only deals with configuring the MAC for a
SFP containing a PHY. Rename it to be specific.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>