net: phy: mdio-gpio: Parse properties directly into bitbang structure

The same parsing code can be used for both OF and platform devices, if
the platform device uses a gpiod_lookup_table. Parse these properties
directly into the bitbang structure, rather than use an intermediate
platform data structure.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>