staging: wfx: fix DT bindings location

Currently, the DT bindings the wfx driver cannot be processed by make
dt_binding_check. We need to place it somewhere into
Documentation/devicetree/bindings/.

After that change, we are able to get warnings from dt_binding_check and
fix them.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20220217103248.183770-1-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>