staging: wfx: do not probe the device if not in the DT

staging: wfx: do not probe the device if not in the DT

Since the WF200 VID/PID are not reliable, it's recommended to declare it
in the DT. Until now, if the device was not declared, the driver just
printed a warning and continue. But, the risk of a collision is too
high, the driver now returns an error.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20220113085524.1110708-32-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>