arm/ls102xa: Add little-endian mode support for audio IPs

As SCFG_ENDIANCR register is added to choose little-endian or big-endian
for audio IPs on Rev2.0 silion, little-endian mode is selected.

Signed-off-by: Alison Wang <alison.wang@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>