staging: unisys: visorchannel.c fix spacing around cast

Clean up the following checkpatch.pl --strict checks:

CHECK: No space is necessary after a cast
+       buf = (u8 *) __get_free_page(GFP_KERNEL);

CHECK: No space is necessary after a cast
+       free_page((unsigned long) buf);

CHECK: spaces preferred around that '+' (ctx:VxE)
+                           SIG_QUEUE_OFFSET(&channel->chan_hdr, queue)+
\
                                                                       ^

Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>