Enable both touchpad nodes in the devictree and let the HID driver
determine which one is actually populated (by attempting to read from
each i2c address).

Ideally this would not be needed and the boot firmware should instead
enable only the node for the populated touchpad, but this is unlikely to
ever be realised for the X13s.

Note that the pin configuration must currently be moved to the parent
i2c-bus node even though only one of these nodes will ever be
successfully probed on a specific device (e.g. to allow them to be
probed in parallel).
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230324094744.20448-1-johan+linaro@kernel.org