staging: r8188eu: remove the private ioctl "wps_prob_req_ie"

Remove the private ioctl "wps_prob_req_ie", it is mapped to
an empty function.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211226212535.197989-5-martin@kaiser.cx


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