mtip32xx: Change HDIO_GET_IDENTITY to return stored data

For the ioctl command HDIO_GET_IDENTITY, return the stored copy of IDENTIFY
DATA instead of sending the command to the device - similar to libata.

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