dm: core: Don't set pinctrl for pinctrl devices

dm: core: Don't set pinctrl for pinctrl devices

There is sort-of race condition when a pinctrl device is probed. The pinctrl
function is called which may end up using the same device as is being
probed. This results in operations being used before the device is actually
probed.

For now, disallow pinctrl operations on pinctrl devices while probing. An
alternative solution would be to move the operation to later in the
device_probe() function (for pinctrl devices only) but this needs more
thought.

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