drivers: ethernet: fix adin2111 devicetree init to work with adin1110

The initialisation of the device data struct was giving a build error
when using the adi,adin1110 devicetree compatible.
Fixed to allow both adi,adin2111 and adi,adin1110 devices to
be defined.

Signed-off-by: Jason Murphy <jason.murphy@analog.com>