ASoC uses the standard ALSA data format definitions to specify the wire
format used between the CPU and CODEC. Since the ALSA data formats all
include the endianess of the data but this information is not relevant
by the time the data has been encoded onto the serial link to the CODEC
this means that either all the CODEC drivers need to declare both big and
little endian variants or the core needs to fix up the format constraints
specified by CODEC drivers.

For now take the latter approach - this will need to be revisited if any
CODECs are endianness dependant.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>