BACKPORT: Fix segfault of qemu-system-arm with PXA target

qemu-system-arm (0.10.5) segfaults when invoked with a PXA machine target,
e.g. -M tosa. The reason is fairly obvious:

[backport: current code uses struct scoop_info_s instead of a typedef ]

Signed-off-by: Torsten Duwe <duwe@lst.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrzej Zaborowski <balrogg@gmail.com>
Signed-off-by: Glauber Costa <glommer@redhat.com>

hw/zaurus.c

@@ -160,7 +160,7 @@ static CPUWriteMemoryFunc *scoop_writefn[] = {
 
 void scoop_gpio_set(void *opaque, int line, int level)
 {
-    struct scoop_info_s *s = (struct scoop_info_s *) s;
+    struct scoop_info_s *s = (struct scoop_info_s *) opaque;
 
     if (level)
         s->gpio_level |= (1 << line);