Staging: unisys: visorchannel: Clean up sparse warnings in visorchannel code

Clean up code to get rid of sparse warnings, mostly due to accessing I/O space.

Remove visorchannel_get_safe_queue(), visorchannel_safesignalremove(),
and visorchannel_safesignalinsert() since they were not called from anywhere.

Signed-off-by: Ken Cox <jkc@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>