[SCSI] fix scsi process problems and clean up the target reap issues

In order to use the new execute_in_process_context() API, you have to
provide it with the work storage, which I do in SCSI in scsi_device and
scsi_target, but which also means that we can no longer queue up the
target reaps, so instead I moved the target to a state model which
allows target_alloc to detect if we've received a dying target and wait
for it to be gone.  Hopefully, this should also solve the target
namespace race.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_sysfs.c

@@ -256,7 +256,9 @@ static void scsi_device_dev_release_usercontext(void *data)
 
 static void scsi_device_dev_release(struct device *dev)
 {
-	scsi_execute_in_process_context(scsi_device_dev_release_usercontext,	dev);
+	struct scsi_device *sdp = to_scsi_device(dev);
+	execute_in_process_context(scsi_device_dev_release_usercontext, dev,
+				   &sdp->ew);
 }
 
 static struct class sdev_class = {