sbp2: fix check of return value of hpsb_allocate_and_register_addrspace

I added a failure check in patch "sbp2: variable status FIFO address
(fix login timeout)" --- alas for a wrong error value.  This is a bug
since Linux 2.6.16.  Leads to NULL pointer dereference if the call
failed, and bogus failure handling if call succeeded.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

Index: linux-2.6.17-rc5/drivers/ieee1394/sbp2.c
===================================================================
--- linux-2.6.17-rc5.orig/drivers/ieee1394/sbp2.c	2006-06-03 01:52:54.000000000 +0200
+++ linux-2.6.17-rc5/drivers/ieee1394/sbp2.c	2006-06-03 01:54:23.000000000 +0200
@@ -845,7 +845,7 @@ static struct scsi_id_instance_data *sbp
 			&sbp2_highlevel, ud->ne->host, &sbp2_ops,
 			sizeof(struct sbp2_status_block), sizeof(quadlet_t),
 			0x010000000000ULL, CSR1212_ALL_SPACE_END);
-	if (!scsi_id->status_fifo_addr) {
+	if (scsi_id->status_fifo_addr == ~0ULL) {
 		SBP2_ERR("failed to allocate status FIFO address range");
 		goto failed_alloc;
 	}