staging: unisys: visorchannel some general function cleanups

Just some cleanups for visorchannel.c, and removal of
safe_sig_queue_validate() which is dead code.

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>