staging: r8188: remove the dummy ioctl handler

staging: r8188: remove the dummy ioctl handler

The r8188 driver installs a dummy handler for some unused ioctls. All
that the dummy handler does is return -1.

Remove the dummy handler and let the wext core handle unused ioctls.
This way, user space gets a consistent errno for an unused wext ioctl,
regardless of which driver is used for the interface.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211218120423.29906-3-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>