net: ftgmac100: convert to driver model

The driver is based on the previous one and the code is only adapted
to fit the driver model. The support for the Faraday ftgmac100
controller is the same with MAC and MDIO bus support for RGMII/RMII
modes.

Configuration is updated to enable compile again. At this stage, the
driver compiles but is not yet functional.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>