staging: r8188eu: rtw_set_ips_deny is not used

Remove the rtw_set_ips_deny function since it's not used.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210913185110.3065-7-martin@kaiser.cx


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