net: phy: split out 10G genphy support

Move the old 10G genphy support to sit beside the new clause 45 library
functions, so all the 10G phy code is together.

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