staging: unisys: visorchannel cleanup visorchannel_create_guts()

The error handling in this function was broken and while looking at that
I noticed that the whole function was in need of cleanup.  This patch
fixes the error handling, specifically

                if (!p) {
                        visorchannel_destroy(p);
                        channel = NULL;
                }

and does a lot of cleanup.  I also verified that the called functions
returned correct errors, and that led to a change in
visor_memregion_resize(), visorchannel_destroy() and
visor_memregion_destroy().

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>