mtip32xx: Fix to make lba address correct in big-endian systems

Earlier lba address was assigned directly to lba_low and lba_low_ex,
which would result in a different number (bytes reversed) in
big-endian systems. Now assigning lba address byte-by-byte to fis.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
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>