hpsa: fix bad comparison of signed with unsigned in hpsa_update_scsi_devices

rescan_hba_mode was defined as a u8 so could never be less than zero:

        rescan_hba_mode = hpsa_hba_mode_enabled(h);
        if (rescan_hba_mode < 0)
                goto out;
Signed-off-by: Joe Handzik <joseph.t.handzik@hp.com>
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/hpsa.c

@@ -3020,7 +3020,7 @@ static void hpsa_update_scsi_devices(struct ctlr_info *h, int hostno)
 	int reportlunsize = sizeof(*physdev_list) + HPSA_MAX_PHYS_LUN * 24;
 	int i, n_ext_target_devs, ndevs_to_allocate;
 	int raid_ctlr_position;
-	u8 rescan_hba_mode;
+	int rescan_hba_mode;
 	DECLARE_BITMAP(lunzerobits, MAX_EXT_TARGETS);
 
 	currentsd = kzalloc(sizeof(*currentsd) * HPSA_MAX_DEVICES, GFP_KERNEL);