scsi: hpsa: Fix boot on ia64 (atomic_t alignment)

Boot failure was observed on an HP rx3600 ia64 machine with RAID bus
controller: Hewlett-Packard Company Smart Array P600:

    kernel unaligned access to 0xe000000105dd8b95, ip=0xa000000100b87551
    kernel unaligned access to 0xe000000105dd8e95, ip=0xa000000100b87551
    hpsa 0000:14:01.0: Controller reports max supported commands of 0 Using 16 instead. Ensure that firmware is up to date.
    swapper/0[1]: error during unaligned kernel access

The unaligned access comes from 'struct CommandList' that happens to be
packed. Commit f749d8b ("scsi: hpsa: Correct dev cmds outstanding for
retried cmds") introduced unexpected padding and unaligned atomic_t from
natural alignment to something else.

This change removes packing annotation from a struct not intended to be
sent to controller as is. This restores natural `atomic_t` alignment.

The change was tested on the same rx3600 machine.

Link: https://lore.kernel.org/r/20210330071958.3788214-2-slyfox@gentoo.org
Fixes: f749d8b ("scsi: hpsa: Correct dev cmds outstanding for retried cmds")
CC: linux-ia64@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: storagedev@microchip.com
CC: linux-scsi@vger.kernel.org
CC: Joe Szczypek <jszczype@redhat.com>
CC: Scott Benesh <scott.benesh@microchip.com>
CC: Scott Teel <scott.teel@microchip.com>
CC: Tomas Henzl <thenzl@redhat.com>
CC: "Martin K. Petersen" <martin.petersen@oracle.com>
CC: Don Brace <don.brace@microchip.com>
Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Suggested-by: Don Brace <don.brace@microchip.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Sergei Trofimovich

drivers/scsi/hpsa_cmd.h

@@ -452,7 +452,7 @@ struct CommandList {
 	bool retry_pending;
 	struct hpsa_scsi_dev_t *device;
 	atomic_t refcount; /* Must be last to avoid memset in hpsa_cmd_init() */
-} __packed __aligned(COMMANDLIST_ALIGNMENT);
+} __aligned(COMMANDLIST_ALIGNMENT);
 
 /* Max S/G elements in I/O accelerator command */
 #define IOACCEL1_MAXSGENTRIES           24