cciss: fix problem that deleting multiple logical drives could cause a panic

Fix problem that deleting multiple logical drives could cause a panic.

It fixes a panic which can be easily reproduced in the following way: Just
create several "arrays," each with multiple logical drives via hpacucli,
then delete the first array, and it will blow up in deregister_disk(), in
the call to get_host() when it tries to dig the hba pointer out of a NULL
queue pointer.

The problem has been present since my code to make rebuild_lun_table
behave better went in.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

drivers/block/cciss.c

@@ -1693,6 +1693,11 @@ static int rebuild_lun_table(ctlr_info_t *h, int first_time)
 	for (i = 0; i <= h->highest_lun; i++) {
 		int j;
 		drv_found = 0;
+
+		/* skip holes in the array from already deleted drives */
+		if (h->drv[i].raid_level == -1)
+			continue;
+
 		for (j = 0; j < num_luns; j++) {
 			memcpy(&lunid, &ld_buff->LUN[j][0], 4);
 			lunid = le32_to_cpu(lunid);