staging: unisys: remove visornic_ioctl

All it does is return no supported.  Removing the function entirely
accomplishes the same thing

Signed-off-by: Neil Horman <nhorman@redhat.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>