mtip32xx: Fix padding issue

Hi Jens,

Another tiny patch.

Removed __packed before the struct smart_attr and added __packed at end of
the structure to fix padding issue.

Signed-off-by: Selvan Mani <smani@micron.com>
Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>