uboot-phytec

dm: Enable gpio command to support driver model

Now that named GPIO banks are supported, along with a way of obtaining
the status of a GPIO (input or output), we can provide an enhanced
GPIO command for driver model. Where the driver provides its own operation
for obtaining the GPIO state, this is used, otherwise a generic version
is sufficient.

Signed-off-by: Simon Glass <sjg@chromium.org>