net: mdio-gpio: Allow for unspecified bus id
net: mdio-gpio: Allow for unspecified bus id

When the bus id was supplied via a struct platform_device, the driver wasn't
handling -1 to mean an unspecified id of the only instance of this driver,
as the platform spec requires.

Signed-off-by: Bert Vermeulen <7b964cd933b2cc9106deabd4641111826cfbc094@biot.com>
Reviewed-by: Andrew Lunn <02e0a999c50b1f88df7a8f5a04e1b76b35ea6a88@lunn.ch>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs