scsi: Add ata_swap_buf_le16() to support big-endian platforms

Otherwise the output will look like this on MIPS Octeon NIC23:

  Device 0: (0:0) Vendor: ATA Prod.: aSDnsi klUrt aII Rev: 4X11
            Type: Hard Disk
            Capacity: 457862.8 MB = 447.1 GB (937703088 x 512)

instead of this version:

  Device 0: (0:0) Vendor: TA Prod.: SanDisk Ultra II Rev: X411
            Type: Hard Disk
            Capacity: 457862.8 MB = 447.1 GB (937703088 x 512)

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Aaron Williams <awilliams@marvell.com>
Cc: Chandrakala Chavva <cchavva@marvell.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>